POWER SUPPLY UNIT – PSU.

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POWER SUPPLY UNIT – PSU

Cac thiet bi dien tu gia dung hay chuyen dung khong the su dung truc tiep dong dien xoay chieu (AC) tu luoi dien duoc ma phai thong qua bo chuyen doi nham ha the va chuyen thanh dong dien mot chieu (DC) cung cap cho cac linh kien dien tu trong thiet bi do. Cac bo chuyen doi nay duoc goi chung la bo nguon cua thiet bi.

POWER SUPPLY UNIT – PSU - Ban co dau.
POWER SUPPLY UNIT – PSU - Ban khong dau.
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POWER SUPPLY UNIT – PSU.

POWER SUPPLY UNIT – PSU.

I. GIOI THIEU CHUNG VE TAM QUAN TRONG CUA PSU:

Cac thiet bi dien tu  gia dung hay chuyen dung khong the su dung truc tiep dong dien xoay chieu (AC) tu luoi dien duoc ma phai thong qua bo chuyen doi nham ha the va chuyen thanh dong dien mot chieu (DC) cung cap cho cac linh kien dien tu  trong thiet bi do. Cac bo chuyen doi nay duoc goi chung la bo nguon cua thiet bi. Khong ngoai le, may vi tinh cung co bo nguon rieng cua minh, vay bo nguon may tinh  co gi khac biet so voi cac bo nguon thong thuong?

Bo nguon la mot thiet bi phan cung  quan trong, cung cap nang luong hoat dong cho toan he thong. Voi hang loat cong nghe  moi chay doi hoac "2 trong 1" nhu RAM  Dual Channel, dia cung RAID, do hoa  SLI/CrossFire, CPU DualCore... Bo nguon cang tro nen quan trong  hon bao gio het boi no quyet dinh su on dinh cua he thong, tuoi tho cua cac thiet bi phan cung khac. Ganh nang nay da vuot qua kha nang "chiu dung" cua nhung bo nguon khong ten tuoi tren thi truong, ke ca nhung bo nguon noname duoc dan nhan cong suat len den “600 - 700W”?????.

Neu khong cung cap du cong suat dien cho he thong, ban se phai thuong thuc vo so cac loi… tu tren troi roi xuong! Nhe thi may chay i ach, cac game yeu thich bi dung hinh lien tuc,… Nang mot chut thi may dang chay, tu nhien khoi dong lai hoac khoi dong khong duoc,... truong hop xau nhat la ca he thong  ”di toi” keo theo nhieu thiet bi “yeu qui” khac phai di “nam vien”. De thay nhat va cac vi du dien hinh la cac tu tren cac mainboard thuong phong rop len, hoac VGA  cac cua ban bi vo hinh xuat hien cac ky tu la... Nguyen nhan  chan doan duoc luc nay la mot phan do thu pham bo nguon gay ra. Chinh vi vay, viec lua chon mot bo nguon thich hop voi he thong  la dieu ban can xem xet va tinh toan khi chon mua may tinh. Dac biet doi voi nhung linh kien cao cap nhu phan cung may tinh  nhung bo nguon chat luong  kem anh huong rat nghiem trong den do ben va tuoi tho linh kien, day la nhung tac hai ma nguoi dung chi nhan biet duoc sau mot thoi gian  su dung nhat dinh..

Viec lua chon bo nguon da khong duoc nguoi tieu dung  Viet Nam  quan tam dung trong mot thoi gian  dai ngay ca doi voi nhung nguoi am hieu ve ky thuat may tinh. Hoac nguoi tieu dung  chi lua chon san pham  qua nhan mac, cam tinh cua minh cung nhu hinh thuc be ngoai ma chua thuc su nam bat duoc nhung thong so ky thuat  cua nha san xuat  cung cap kem theo san pham (tat nhien con tuy thuoc do trung thuc vao nha cung cap  hoac san xuat – duoc dam bao chac chan tu nhung san pham va nha san xuat  co ten tuoi..).

Voi nhung ly do  tren chung toi  da chon loc va suu tam tong hop cac thong tin bai viet tren cac dien dan  phan cung, tap tri tin hoc  uy tin trong va ngoai nuoc cung nhu tham khao cac thong tin  tren Internet  cac van de lien quan den bo nguon cua may tinh  de nguoi su dung  tien cho viec tham khao tra cuu…


II. BO NGUON MAY TINH NO LA GI?

Hien nay co 3 dang chuyen doi nang luong dien thong dung sau:

Chuyen tu AC sang DC: thuong dung lam nguon cap cho cac thiet bi dien tu  (adaptor, sac pin…).

Chuyen tu DC sang DC (Convertor): chuyen doi dien the DC ra nhieu muc khac nhau.

Chuyen tu DC sang AC ( Invertor): thuong dung trong cac bo luu dien du phong (UPS,…).

Cac thanh phan mot bo nguon thong thuong hoan chinh se co bao gom cac thanh phan:

+ Bo bien ap: ha ap cua dien luoi xuong mot muc thich hop cho thiet bi. Dien the ra cua bien ap van la dang dien xoay chieu nhung co muc dien ap thap hon. No con co nhiem vu cach ly cho thiet bi voi dien the luoi.

+ Bo nan dien (chinh luu): chuyen doi dien the xoay chieu thanh mot chieu (DC). Chinh luu con gon song, cac mach dien tu  trong thiet bi chua the su dung duoc dien the nay.

+ Bo loc chinh luu: thanh phan chinh la tu dien co nhiem vu giam gon song cho dong dien DC sau khi duoc chinh luu.

+ Bo loc nhieu dien: de tranh cac nhieu va xung dien tren luoi dien tac dong khong tot den thiet bi, cac bo loc se gioi han hoac triet tieu cac thanh phan nay.

+ Mach on ap: on dinh dien ap cung cap cho thiet bi khi co su thay doi boi dong tai, nhiet do va dien ap dau vao.

+ Mach bao ve: lam giam cac thiet hai cho thiet bi khi co cac su co do nguon
dien gay ra (qua ap, qua dong, …).


Mot bo nguon ly tuong la bo nguon co dien ap ra on dinh, bang phang, khong gon song (tuong tu nhu dong dien duoc tao ra tu cac bo pin), khong toa nhiet va co hieu suat  dat 100%. Bo nguon trong may tinh  con duoc goi bang ten khac la PSU ( Power  Supply Unit ) la noi cung cap nang luong chinh cho he thong  may tinh. Tat ca cac bo nguon cua may tinh deu hoat dong  dua theo nguyen tac nguon chuyen mach tu dong (switching power  supply) voi cach thuc hoat dong  nhu sau: dien xoay chieu tu luoi dien duoc bo chinh luu nan thanh dong dien mot chieu chinh luu. Dong dien nay duoc cac bo loc gon song (tu dien co dung luong lon) lam cho bang phang lai thanh dong dien mot chieu cap cho cuon so cap cua bien ap xung (transformer).

Dong dien nap cho bien ap xung nay duoc dieu khien boi cong tac ban dan (transistor switching). Cong tac ban dan nay hoat dong  duoi su kiem soat cua khoi do sai / hieu chinh, tu truong bien thien duoc tao ra tren bien ap xung nho cong tac ban dan hoat dong  dua tren nguyen tac dieu bien do rong xung (PWM-Pulse Width Modulation). Xung dieu khien nay co tan so rat cao tu 30~150Khz (tuc la co tu 30 ngan ~150 ngan chu ky trong mot giay). Tan so nay duoc giu on dinh va do rong cua xung se duoc thay doi khi co su hieu chinh tu bo do sai / hieu chinh. Tu truong do cam ung len cac cuon day thu cap tao ra cac dong dien xoay chieu cam ung (dang xung) se duoc cac bo chinh luu so cap nan lai lan nua. Sau do, qua cac bo loc so cap, dong dien mot chieu tai day da san sang cho cac thiet bi su dung.


De nhan biet duoc sai lech ve dien ap hay dong dien cua cac duong dien the o cac ngo ra, tu day se co mot duong hoi tiep do sai (feedback) dua dien ap sai biet ve bo do sai / hieu chinh. Khoi nay nhan cac tin hieu sai biet va so sanh chung voi dien ap chuan, sau do tac dong den cong tac ban dan bang cach gia giam do rong xung de hieu chinh lai dien the ngo ra (on ap) hay cat xung hoan toan lam bo nguon ngung “chay” trong cac che do bao ve. Uu diem cua bo nguon switching la gon nhe (do hoat dong o tan so cao nen co cac linh kien nho gon hon), hieu suat  cao va co gia thanh thap.


III. CAC DUONG DIEN THE CHUAN TRONG BO NGUON:

-12V: cung cap chu yeu cho cong song song  (serial port-COM) va cac chip  khuech dai am thanh can den nguon doi xung +/-12V. Duong nay co dong thap duoi 1A (Ampe).

-5V: hien nay cac thiet bi moi khong con dung duong dien nay nua. Luc truoc, no duoc dung cung cap dien cho card  mo rong dung khe cam ISA. Duong nay cung co dong thap duoi 1A.

0V: con duoc goi la duong dung chung (common) hay duong dat (ground). Duong nay co hieu dien the bang 0V. Do la muc nen cho cac duong dien khac thuc hien tron ven viec cung cap dong dien cho thiet bi.

+3.3V: la duong cung cap chinh cho cac chip, bo nho (memory), mot so thanh phan tren bo mach chu, card  do hoa  va cac card  su dung khe cam PCI.

+5V: duong dien duoc dung pho bien nhat trong may tinh  cung cap dien chu yeu cho bo mach chu, cac CPU doi cu, cac chip  (truc tiep hay gian tiep) va cac thiet bi ngoai vi khac. Hien nay cac CPU da chuyen sang dung duong dien the 12V.

+12V: chu yeu su dung cho cac dong co (motor) trong cac thiet bi luu tru, o quang , quat, cac he thong  giai nhiet va hau het cac thiet bi doi moi hien nay deu su dung duong dien 12V CPU PIV, Althlon 64, dual core AMD, Pentium D, VGA  ATI, NVIDIA SLI, ATI Crossfire..

+5VSB (5V Standby): la nguon dien duoc bo nguon cap truoc, dung phuc vu cho viec khoi dong may tinh, nguon dien nay co lap tuc khi ta noi bo nguon vao nguon dien nha (AC). Duong dien nay thuong co dong cung cap nho duoi 3A.

IV. CONG SUAT GIUA CAC DUONG 3.3V, 5V, 12V LIEN QUAN GI NHAU?

Cac bo nguon chuan AT thuong co cong suat cac duong 3.3V va 12V thap. Hien nay voi cac bo nguon su dung chuan ATX, cac duong nay co cong suat kha cao va tuong duong nhau. He so cong suat cua ba duong chinh nay duoc mo ta trong huong dan  thiet ke  chuan ATX12V phien ban  2.2. Hien nay, bo nguon co cong suat cao la nho chu yeu dua vao duong 12V co dong ra cao hon cac bo nguon cu nham dap ung nhu cau “ngon”dien cua cac CPU moi. Tuy nhien cong suat tren cac duong dien 3.3V, 5V va 12V co su lien quan voi nhau.

Vi du voi mot bo nguon co tong cong suat danh dinh la 430W, thoat nhin ta se thay co su bat hop ly vi khi cong suat tinh dua vao bang mo ta cua nha san suat thi tong cong suat phai la 666.9W. Neu chu y mot chut, ta se thay cong suat toi da cua duong 3.3V va 5V bang 230W, 12V bang 336W. Su that o day la khi hai duong cong suat 3.3V va 5V dat 230W thi duong 12V chi dat duoc cong suat 172W hoac nguoc lai neu duong 12V dat cong suat 336W thi hai duong con lai chi con 66W ! . Quy luat bu tru cong suat tren la do phu thuoc vao kha nang cung cap cong suat toi da cua bien ap xung va do ba duong dien chinh nay co su lien he mat thiet voi nhau. Nen hien nay, doi voi cac gia tri  cong suat duoc in tren cac nhan cua bo nguon thuong co hai dang la cong suat toi da (maximum) hay cong suat dinh (peak) la cong suat toi da ma bo nguon co the dap ung duoc trong mot khoang thoi gian nhat dinh va cong suat hieu dung total power) hay cong suat lien tuc (continuous) la cong suat ma bo nguon co the hoat dong  lien tuc an toan.

Loi khuyen: ban chi nen tin khoang 90% nhung gi ghi tren bo nguon va cac thong so tren chi ap dung cho cac bo nguon co chat luong  tot.

V. VAN DE LIEN QUAN DEN CONG SUAT BO NGUON

Hien nay, mot cau hinh trung binh can phai co mot bo nguon co cong suat hieu dung toi thieu la 300W. Xin duoc noi ro o day, cong suat hieu dung la cong suat ma bo nguon co the cung cap lien tuc va on dinh cho he thong. Con cong suat ghi tren vo duoc goi la cong suat danh dinh. Thuong thi cong suat nay chi mang tinh chat quang cao  (cac thong so nay neu dat duoc nhu quang cao  cua nha san xuat thong thuong duoc thu nghiem  trong cac dieu kien phi thuc te..???...).

Ban nen biet he thong  cua ban co cong suat tieu thu la bao nhieu cho cac linh kien phan cung  trong may tinh  cua ban:

Tham khao tai website:

http://www.extreme.outervision.com/psucalculator.jsp
http://www.jscustompcs.com/power_supply

O cac trang web  nay, ban chon cac thiet bi cua minh hien co (hoac se co) va website  se tu dong tinh ra tong cong suat cho ban. Dua vao ket qua nay, ban co the yen tam chon mot bo nguon cong suat hieu dung thich hop roi cong them mot he so an toan duoi day:

+Voi cac bo nguon noname TQ gia sieu re: cong them 30% den 50% tong cong suat.

+Voi cac bo nguon da co ten tuoi va dat tien hon nhung ban khong chac chan tin tuong vao cong suat dinh cua bo nguon: cong them 15% den 25% tong cong suat..

+Cac bo nguon lam viec  24/7 voi thoi gian  su dung qua 1 nam: ban cung nen cong them it nhat tu 15% den 30% tong cong suat..

Luu y: khi lap cac bo nguon khong dap ung duoc cac yeu cau cong suat tren, he thong  cua ban van co the hoat dong  duoc nhung he so an toan va on dinh dat duoc la rat thap. Doi voi cac he thong  su dung cac ung dung  binh thuong (ung dung van phong,duyet web…it khi chay toan tai hieu nang cua may) ban van co the duy tri su dung cac bo nguon nay voi ly do  tiet kiem. Nhung khi he thong  cua ban luon phai lam viec voi ap luc lon va lien tuc (cac ung dung  tro choi, do hoa, multimeadia.. yeu cau chay toan tai vat kiet hieu nang cua ca he thong) thi van de cong suat nguon khong dap ung noi he thong  tro thanh van de het suc quan trong  doi voi he thong  cua ban. Hien tuong “lam sang” de dang nhan biet cua bo nguon chay qua cong suat: co mui la, vo cua bo nguon nong bat thuong va tat nhien la cac hien tuong he thong  lam viec khong on dinh (nhanh cham that thuong, treo, khoi dong lai, bao loi man hinh xanh..)..

Cac bo nguon noname ban kem theo thung may (case) hien nay thuong co chat luong thap. Voi cac bo nguon hang hieu co chat luong  tot nhu Thermaltake, Enermax, Antec, CoolerMaster, AcBel, SilverStone… cong suat hieu dung thuong bang hoac lon hon cong suat dinh danh.

VI. DIEN THE

Trong may tinh, cac thiet bi thuong khong su dung truc tiep  dien ap tu bo nguon ma phai qua cac mach on ap cua rieng thiet bi do. Cho nen, mot bo nguon cap du dien the va dien the ay on dinh se mang lai tuoi tho cao cho cac thiet bi. Mot bo nguon tot thuong co cac duong dien chinh (5Vsb, 3.3V, 5V va 12V) co muc dien the nam trong khoang +/- 5% dien the chuan va rat it dao dong. De xem duoc dien the nay, ngoai cac thiet bi do chuyen dung nhu dong ho  do dien (VOM- Volt Ohm Milliemmeter hay DMM - DigitalMultimeter), ban co the xem qua phan mem  tien ich hien thi thong so he thong  kem theo mainboard hoac cac phan mem  mien phi  nhu Speedfan hay Sisoft Sandra. Do phan mem  doc so do qua sensor cua bios, nen gia tri  doc thuong thap hon gia tri  thuc tu 0.1V ~ 0.6V.

VII. CAC CHE DO BAO VE

Bo nguon la mot thiet bi cong suat hoat dong  lien tuc trong moi truong khac nghiet, voi dong chiu tai cao nen hai che do bao ve can ban nhat can phai co la bao ve qua ap va bao ve cham tai. Chung giup bo nguon bao ve thiet bi va tu bao ve minh khoi cac su co xay ra khi van hanh.

Bao ve qua ap: vi mot ly do  nao do ma mach nan dien va on ap cua bo nguon co su co, lam cho dien the o cac duong cap dien tang cao. Bo nguon se tu ngung hoat dong  de khong gay thiet hai cho cac thiet bi khac. Nguong dien the cat cua bo nguon con tuy thuoc vao nha san suat. Moi bo nguon khac nhau se co muc cat khac nhau.

Bao ve cham tai: che do nay kha quan trong  vi no se bao ve cho bo nguon khi cac duong dien bi cham (doan mach). Bo nguon se ngung hoat dong de tu bao ve va hoat dong  tro lai khi da het doan mach. Neu co du can dam, ban co the thu tinh nang nay bang cach dung day chung (day co mau den) lan luot cham nhanh vao cac duong dien cua bo nguon. Neu bo nguon co che do bao ve nay thi no se ngung chay ngay lap tuc. Doi voi mot bo nguon co chat luong  tot, che do bao ve cham tai co tren tat ca cac duong dien chinh. Con voi cac bo nguon re tien, che do bao ve nay thuong chi co tren mot hoac hai duong dien chinh (tham chi khong co).

Cac che do bao ve khac: cac bo nguon cao cap con co them mot so che do bao ve khac nhu: qua dong, qua tai, qua nhiet cho bo nguon, qua nhiet cho he thong… Cac che do bao ve nay lam tang do an toan, gia tri cho bo nguon va cho ca he thong.

VIII. VAN DE HIEU SUAT CUA CAC BO NGUON

Hieu suat cua mot bo nguon duoc the hien qua ti le nang luong tieu thu dau vao (AC in) va nang luong tao ra (DC out) cho he thong. Gia tri thuong dung de tinh la Watts. Bat cu mot vat gi sinh ra cong deu khong the dat duoc hieu suat  toi da 100% do mot phan cong nang bi tieu ton duoi dang nhiet. Bo nguon cung vay, chua co va cung se khong co bo nguon nao dat duoc hieu suat  ly tuong 100%. Nhung chung ta co gang khong su dung cac bo nguon co hieu suat  qua thap vi ly do  kinh te  la chinh. Neu bo nguon tieu thu mot luong dien la 400W (AC in) de cho ra mot cong suat 320W (DC out) thi ta co the noi bo nguon nay co hieu suat bang 80% va 20% (80 W) con lai bi mat di duoi dang nhiet. Co mot dieu ban can luu y la 80W nay thuc su khong mat di hoan toan, ma no se “the hien” trong…hoa don tien dien hang thang cua ban. Khong nhung vay, no con khien moi truong  lam viec  cua ban nong hon. Va ban lai phai ton them mot khoang nang luong de lam mat cho chinh minh. Nhu vay, so huu mot bo nguon co hieu suat  cao dong nghia voi viec tiet kiem  nang luong dien. Bo nguon se hoat dong  em hon do co nhiet do thap hon va van de nhiet do he thong  khong con la noi lo hang ngay cua ban.

IX. CAC DAU CAM PHO BIEN CUA BO NGUON

So luong dau cam quyet dinh  kha nang gan them thiet bi (o cung, cac loai o quang,…) cho he thong  cua ban. Ngoai cac dau cap nguon chinh (ATX 20 chan hoac 24 chan), 12V (4 chan) thi cac dau cap nguon cho thiet bi ngoai vi cang nhieu cang tot. Mot so bo nguon cao cap con duoc trang bi them cac dau cam 12V (6 chan) cho card  do hoa PCI Express, cac dau cap nguon danh rieng cho cac o cung  chuan SATA,…


X. HE THONG THOAT NHIET CHO NGUON

De giai quyet van de nhiet do cho cac linh kien cong suat trong bo nguon, tat ca cac bo nguon hien nay deu dung phuong phap tan nhiet bang khong khi la chinh (dung quat de lam mat). Quat thong dung nhat co kich thuoc 80mm hoac 120mm, toc do quay tu 2.200 ~ 3.500 vong/phut. Quat co toc do quay cang cao thi viec tan nhiet cang hieu qua nhung do on cung tang theo. Khi cong suat bo nguon tang do nhu cau cua he thong, van de giam nhiet do cho linh kien trong bo nguon cang duoc cac nha san xuat quan tam hon. Ho dua ra nhieu cai tien nhu tang toc do quat, them tinh nang “quat thong minh  – smart fan”, su dung hai quat (mot hut, mot day), su dung quat lon (120 den 150 mm), lam cac khoi kim loai tan nhiet “ham ho“ hon hoac ket hop cac cach tren lai voi nhau.

XI. CAC CHUAN ATX 1.3 VA 2.X:

Hien tai 2 chuan ATX pho bien la chuan 1.3 va chuan 2.x (ben canh cac chuan danh cho server  cua INTEL  va AMD - xin phep khong lam ban o day).

ATXV1.3: chi co 1 duong (rail) 12V va co the co hoac ko co dau cap nguon SATA, thuong thi cac PSU chuan ATX V1.3 co hieu suat  thap – chi dat ~ 60 % - Va co duong dien chinh la duong 5V (cong suat 5V rat cao) (thich hop cho nhung main  cap 5V cho CPU the he cu).

ATX 2.x: co duong dien chinh la duong 12V (max la 18A cho moi rail doi voi PSU co 2 rail 12V , neu vuot qua gioi han tren thi do nhieu se tang nhung hien da co mot so nguon moi vuot qua duoc 18A..????..) trang bi dau cap nguon SATA (bat buoc), cap nguon PCie (VGA), 12V+ (cho main  board) ben canh nhung dau cap nguon HDD, Floopy thong thuong, hieu suat  cua PSU ATXV2.x thuong dat >70% mot so PSU cao cap co the len toi 80%. Theo xu huong thoi dai , chuan ATX 2.x da va dang dan thay the chuan ATX 1.3.

XII. CAU HOI LIEN QUAN, TINH NANG, THONG SO KY THUAT CUA PSU?

Trong phan tiep theo nay chung toi  tap trung vao giai dap cac cau hoi thac mac ma nhung nguoi tieu dung  thuong quan tam  den khi lua chon cac bo nguon. Ngoai ra chung toi  cung giai dap mot so thuat ngu va cac tinh nang ky thuat  thuong thay xuat hien tren cac san pham  nguon may tinh thuong thay tren thi truong  Viet Nam:

1. Tai sao toi can hon 1 duong 12V cho cac PSU doi moi?

Khong nhung co 2 ma trong can san pham cao cap  gan day cac nha san xuat da co nhieu san pham  co den 3 tham chi 4 duong 12V, boi mot dieu don gian hau het cac thiet bi doi moi hien nay deu su dung duong dien 12V (CPU Intel  P4, Althlon 64, DualCore AMD, Pentium D, VGA  ATI, NVIDIA, cac cong nghe  SLI, ATI Crossfire, va sap toi hang loat the he CPU moi cua Intel  cung AMD se ra doi deu su dung duong dien 12V) vi vay de dam bao van de an toan dien va do nhieu dua theo chuan UL\EN – UL\EN (cost lists a maximum of 240VA per circuit) nen cap them 1 rail 12V cho PSU la giai phap can thiet. Ben canh do may tinh  ngay nay con phai gong ganh nhung thiet bi dien ap tang giam dot ngot nhu den, FAN sieu cap, Pump, Peltier .... lam anh huong den cac thiet bi truyen thong  nhu main, cpu, vga  von hoat dong  kha on dinh va can do on dinh dien ap tot. Hien nay PSU ATXV2.x co 2 rails 12V la pho bien nhat (va theo thiet ke cung la phu hop nhat so voi 3 hay 4 rails) voi muc dich phuc vu (tren ly thuyet) nhu sau:

12V1 : Main  board ATX 24 pin  , HDD, SATA , Floppy...
12V2 : Tap trung tai cac thiet bi khung bo  nhu VGA  PCI-E va 12V+ cho main  board doi moi.

Thuc te thi khi thiet ke  cac nha san xuat  co nhieu ly do  de thay doi chuc nang cua 2 rail tren, vi thuc chat 2 rail nay thuong thong nhau de can bang tai (dieu nay khien 2 rail co dien the can bang mac du tai o 2 rail la chenh lech dang ke)

2. Passive P.F.C / Active P.F.C la gi?

Mot van de cung rat duoc nhieu nguoi tieu dung  quan tam  hien nay la PFC (Power Factor  Corrected). Co 2 loai PFC la Active PFC va Passive PFC. Hieu nom na PFC la 1 he thong  bao gom nhieu FET, IC, Diot v.v... (tuy theo thiet ke  cu the cua moi PSU) chuc nang nhu 1 cuon thu cap tao dong dien dong pha va khong doi khi vao cuon chinh cua PSU (tang chat luong va do on dinh cua dong dien) va khong gay nhieu nguoc ve dong dien AC dau vao (dong dien xoay chieu) gay anh huong den cac thiet bi su dung dien AC trong he thong  dien chung (nhat la khi PSU co cong suat lon). Mot loi the nho nho cua Active PFC nua la khi do PSU se khong can cong tac chuyen 110/220V nua cang thuan loi cho nguoi tieu dung  cuoi. Tin mung cho nhung ai thich xai UPS(bo luu dien): thi thoi gian  luu dien se lau hon khi PSU cua ban co Active PFC. Tuy nhien bo tien de sam 1 PSU autovolt input, luu dien lau hon va an toan hon lieu co du thuyet phuc ban chon mua 1 PSU co Active PFC?

Chung ta tam thoi thong qua cong thuc sau:

PF=truepower/totalpower
PF: 1 ty so khong co don vi the hien chat luong  cua bo nguon
truepower: cong suat that (W)
totalpower: cong suat tren ly thuyet (W)

Hay lam 1 so sanh nho:

PSU khong co PFC ty so PF rat thap ~ 0.6 (true power  thap)
PSU trang bi PASSIVE PFC PF la ~ 0.75 - 0.85
PSU trang bi ACTIVE PFC co PF tuyet voi 0.90 ~ 0.99 (true power  cao nhat)

Xin dung nham lan giua Hieu suat  va ty so PF neu tren, boi vi 1 PSU co Active PFC (true power  rat lon) nhung hieu suat  van <80% (ly do la ban than bo phan ACTIVE PFC can cap nguon dau vao de tu van hanh => dien dau vao cua PSU cao hon dan den hieu suat  khong cao) . Hay noi cach khac 1 PSU ACTIVE PFC cho ban 1 true power  "hung manh" va cung su dung them dien de van hanh.

Tom lai neu PSU cua minh co active PFC thi ban co the tin tuong rang PSU cua ban cho ra dong dien rat tot, cong suat lon, on dinh. Day co the la ly do  chinh de ban quyet dinh  dau tu  cho 1 PSU co PFC.

3. PSU doi voi nghe thuat Overclocking - OC?

Co the noi Overclocking la mot mon nghe thuat, Overclocker la nhung nghe si va cac ket qua, cac ki luc ve Overclock la nhung tac pham  nghe thuat. Ban dung xem thuong bo nguon may tinh. Khi ban bat mot thanh phan nao do trong may tinh  chay voi toc do cao hon toc do mac dinh, vd nhu CPU. Neu ban cu tiep tuc tang fsb de nang toc do thi toi mot gioi han nao do no se hoat dong  thieu on dinh, lam may thuong xuyen bi khoi dong lai hoac treo may. Hay tang them dien cho no, tuc la cho no “an” nhieu dien hon so voi dien the mac dinh. That vay, viec tang dien ap cho CPU khi Overclock se giup du lieu  truyen di toi cac thanh phan khac khong bi gian doan va viec thieu dien chinh la nguyen nhan  gay ra su mat on dinh cua he thong. Tuong tu voi cac thanh phan khac cung vay. Hau het, trong viec ep xung cac thiet bi deu tuan theo mot nguyen tac la: toc do ti le thuan voi dien the, tuc la toc do cang cao cang can nhieu dien hon de co the chay on dinh.

Muon OC dat ket qua tot thi ban phai chu y toi bo nguon. Khi tang dien cho cac thanh phan thi bo nguon phai luon dam bao khong bi sut dien bat ngo. Da co truong hop duong dien 12V va 5V bi sut the tham khi keo vcore ( Core Voltage - dien ap CPU ) va vdimm ( dien ap RAM  ) len qua cao trong khi dung bo nguon noname chat luong  kem. Hau qua di nhien la hu hong thiet bi. Mot bo nguon tot cua cac hang co ten tuoi nhu OCZ ModStream, Zippy, Antec, AcBel Real  Power, Thermaltake PurePower, CoolerMaster RealPower Series.. se la nen tang tot cho he thong  cua ban truoc khi buoc vao qua trinh Overclock.

4. Tieng on va nhiet do cua PSU – ban co thay kho chiu?

Ban co nghi nhung he thong  may tinh  hien nay tao ra qua nhieu tieng on khong? Du chung ta da bo khong it tien de trang bi nhung bo loa chat luong cao nham thuong thuc am nhac  hay hon, nhung am thanh tu loa cong voi tieng on phat ra tu may tinh  lam cho gian phong tro nen am i va hon loan. Bo phan phat ra nhieu tieng on nhat trong he thong  la quat lam mat va hau het moi may tinh  deu duoc trang bi cung luc nhieu thiet bi nay. Di nhien, nhung chiec quat nay co chuc nang lam mat cho thanh phan ben trong thung may va do la mot nhiem vu het suc quan trong. Tuy nhien voi su lua chon dau tu  phu hop, ban co the vua bao ve may tinh  de nhiet do khong qua nong vua van hanh em ai hon.

Voi nhung bo nguon it ten tuoi tren thi truong van de nay kho co the lam hai long duoc ban. He thong  tan nhiet cho cac loai nguon nay hau nhu co de tuong trung bang cach su dung cac loai quat chat luong  kem va it khi quan tam  den thiet ke  AirFlow toi uu. Sau thoi gian  ngan su dung hau het deu co van de ve do on va nhiet do. Voi nhung san pham  ten tuoi thi khac han ngoai chuc nang tu lam mat cho cac linh kien cua minh nhung bo nguon nay con co nhiem vu giai phong mot phan dang ke khi nong trong thung may. Hau het deu duoc trang bi cac loai quat chat luong  cao toc do tu dieu chinh thong minh  theo nhiet do va do on deu duoc kiem soat mot cach hoan hao. Do on cua cac san pham  nay thuong dao dong trong khoang tu 16dBA den tren 20dBA.. Bang duoi day se mang lai cho ban su so sanh thu vi ve do on:

Muc am thanh | Nguon phat am va khoang cach tuong duong

180 dBA: Dong co ten lua khoang cach 30m
150 dBA: Dong co phan luc o khoang cach 30m
130 dBA: Nguong dau tai khi ban nghe am thanh muc do nay
120 dBA: May bay cat canh o khoang cach 100m, trong buoi bieu dien  Rock
110 dBA: Dong co moto  GP tang toc o khoang cach 5m
100 dBA: Dong co thiet giap o khoang cach 1m, hoac giua san nhay disco..
90 dBA: Dong co cua xe tai hang nang o khoang cach 1m
80 dBA: Am thanh cua may bom hay may hut bui o khoang cach 1m
70 dBA: Nhu am thanh khi vu tac duong o khoang cach 5m
60 dBA: Giua van phong  lam viec  hoac tiem an
50 dBA: Quan an thua khach
40 dBA: Su yen lang khu dan cu vao ban dem
30 dBA: Nhu su im lang trong nha hat  khi khong co nguoi noi
20 bBA: Tieng xao xac cua la cay la
10 dBA: Hoi tho binh thuong cua mot nguoi o khoang cach 3m
0 dBA: Muc khong the nghe thay gi

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Updated: 03/03/2008 | Views: 360 | Comments: 0

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