Go Back   nV News Forums > Hardware Forums > General Hardware

Newegg Daily Deals

Reply
 
Thread Tools
Old 04-13-09, 07:01 PM   #1
boredgunner
NVIDIA/Intel User
 
boredgunner's Avatar
 
Join Date: Jan 2009
Location: Lingshan Islands
Posts: 32
Default How to Determine REAL +12v Amperage on Your PSU

I'd like to mention an equation that would let you find how out much amperage your PSU has on the +12v rail(s). The +12v rails are probably the most important rails on a PSU since they supply the power to the CPU and GPU. People usually overlook this part of a PSU, in fact they tend to just buy cheaper PSUs in general which will cause many issues.

If you look on the sticker, near the +12v area, you'll see the amperage of the +12v rail(s), and under that a power measurement in watts. Lets look at my PSU for example, the COOLER MASTER Real Power Pro 650W.



See, three +12v rails with 19A on each and beneath it 540W. This means the +12v rails combined generate 540W of power at max load. Since 540W is the +12v power, divide 540 by 12 to get the real amperage, don't do 19 times 3 since that gives you 57.

Correct Way:
540W/12v = 45A - nice value by the way

Incorrect Way:
19A + 19A + 19A = 57A

Why is that incorrect?
57A x 12v = 684W - this is a 650W PSU

NOTE: This does not have to be done for a PSU with a single +12v rail. Lets use the COOLER MASTER Silent Pro M 600W for example.



It tells you right there it has 40A of +12v power. If you have any doubts...

480W/12v = 40A

I prefer multiple +12v rail power supplies since they are more stable (generally speaking). Here is what I recommend you look for in a PSU.
  • Below 400W: Above 20A on the +12v rail(s)
  • 400W-450W: Above 20A on the +12v rail(s)
  • 451W-500W: Above 25A on the +12v rail(s)
  • 501W-550W: Above 30A on the +12v rail(s)
  • 551W-600W: Above 34A on the +12v rail(s)
  • 601W-650W: Above 40A on the +12v rail(s)
  • 651W-700W: Above 45A on the +12v rail(s)
  • 701W-750W: Above 50A on the +12v rail(s)
  • 751W-800W: Above 50A on the +12v rail(s)
  • 801W-900W: Above 60A on the +12v rail(s)
  • 901W-1000W: Above 70A on the +12v rail(s)
  • 1001W-1200W: Above 80A on the +12v rail(s)
Pretty much anything above 1200W has a solid +12v line, but that doesn't mean the unit is good.

Not good at math? Neither am I. Use a calculator!

http://www.calculator.com/pantaserv/makecalc

Also check out my PSU guide.

http://www.evga.com/forums/tm.asp?m=100557126
boredgunner is offline   Reply With Quote
Old 04-14-09, 02:21 AM   #2
bob saget
 
Join Date: Dec 2006
Location: Vancouver, originally Russia
Posts: 23,134
Send a message via MSN to bob saget Send a message via Yahoo to bob saget
Default Re: How to Determine REAL +12v Amperage on Your PSU

nice post!
bob saget is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 09:05 PM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 1998 - 2014, nV News.