Sign in with
Sign up | Sign in
Your question

Need help on choosing PSU (Laymen's term pls)

Last response: in Components
Share
April 24, 2007 12:57:02 PM

i really a noob when it comes to PSU's... and i dont know which to buy, ive already read alot of topics here but i still dont get it... my system is:

Intel C2D E6600
Leadtek 8800 GTS 320 MB
Asus P5B-E Plus
2 Gig Ram Corsair 667
250 GB Seagate Sata
Sony Dvd Combo..

need help... thanks alot !
April 24, 2007 1:09:37 PM

basically, what i understand is... i need to get ATLEAST 400 watts ryt ? and as much as possible it should be Antec or Enermax, ryt ?

what i dont get is the 12v rails.... it confuses me alot... and the vendors here also doesnt know that.
April 24, 2007 1:19:15 PM

yup ! ive read it once... but never understood that much on the 12v rail one.... lemme read it again tomorrow :)  thanks alot !
Related resources
April 24, 2007 5:11:54 PM

Quote:
i really a noob when it comes to PSU's... and i dont know which to buy, ive already read alot of topics here but i still dont get it... my system is:

Intel C2D E6600
Leadtek 8800 GTS 320 MB
Asus P5B-E Plus
2 Gig Ram Corsair 667
250 GB Seagate Sata
Sony Dvd Combo..

need help... thanks alot !


Go here, enter the values of your components - allow for some overhead and pick a reliable brand. Not everybody has the time to read exhaustive stickies (that are overly complex)

PSU Calculator
a b ) Power supply
April 24, 2007 5:39:48 PM

Quote:
i really a noob when it comes to PSU's...


I'll make it easy for you.

1. Do you plan on adding anything else?

2. Will you be overclocking?

3. What's your price range? Roughly guessing you'll need to spend at least $75 for something decent.
a b ) Power supply
April 24, 2007 6:00:40 PM

Actually, I have already answered a similar question today:

Quote:
Actually, the Seasonic S12 430 with 29A on the 12v rails is more than enough for the system even when overclocked.

C2D E4300 OCed to X6800 speed (2.93GHz).................66w CPU Power Consumption Link
Radeon X1950XTX........................................................125w GPU Power Consumption Chart Link
1 Hard Drive..................................................................12w
1 DVD Drive...................................................................12w
2 120mm Case Fans at full speed..................................12w
1 120mm CPU at full speed............................................6w

Total max power consumption on 12v rails.....................221w
Total max amp consumption on 12v rails......................18.42a

Note the X1950XTX uses slightly more power than the X1950XT.

That leaves more than 10amps (or 120w) on the 12v rails yet to be used.

Assuming linear CPU power consumption in relation to clock speed, for every 300MHz above the speed of the stock X6800 CPU, add another 8w to the power consumption.


Your 8800GTS 320 uses about 105w - 115w which is less than the 125w for the X1950XTX in the above example.

The Seasonic S12 430 can easily handle your system even if you overclock and you will still have some power left over.

You can purchase the Seasonic S12 430 for $75 + shipping. Seasonic makes excellent PSUs that are reliable, quiet and power efficient.

http://www.xpcgear.com/s12430.html


If you feel 430w seems "too weak" then I suppose you can get it's bigger brother, the S12 500 for $103 + shipping:

http://www.xpcgear.com/s12500.html
April 24, 2007 6:03:06 PM

The way I do it is to use the above PSU calculator and enter the components that use 12v, i.e:

Processor
1 Hard Drive
1 Optical drive
Video card

Take the result in Watts and divide it by 12. That give you the requirement in amps on the 12v rails. Look for a power supply that can deliver that amount plus 2-4 amps for safety margin on the 12v rails. You don't want your power supply to be at 100% utilization all the time.
You are most concerned with what a power supply can deliver on the 12v rails.
a b ) Power supply
April 24, 2007 6:17:24 PM

When I initially used the PSU calculator a couple of years ago, I found that it was very inaccurate. For example, it uses TDP which is not exactly the same as actual power consumption. I prefer to do my own research on the components.

HDDs and DVDs drive are pretty much standard. They use about 12w - 14w on the 12v rail and about 5w on the 5v rail. Of course Raptors and Cheetah drives will use more power since they spin faster.

That pretty much leaves the CPU and GPU. Those are the two most power hungry components that draws power from the 12v rails and can vary a lot depending on the actual component used.

One other thing that I don't like about the PSU calculator is that it gives you the total power not just the 12v rail (unless it's been updated). For the most part, the 12v rail is the most important rail and any current PSU can provide more than enough power on the 3.3v and 5v rails for just about any setup.

-------------------------

In the above setup, the user should have at least 10 amps (120w) left over. Less if the OP decided to overclock his C2D above 2.93GHz.
April 24, 2007 6:54:46 PM

Yes if you are using SLI or RAID use two video cards or hard disks in your calculation.
If you have a spare hard drive, use just one in the calculation. It is assumed that only one hard disk will be in use at the same time.
Same for dual optical drives.
!