Unsure about PSU Specs

johnross2007 · November 3rd, 2009, 09:53 AM

Howdy guys, haven't been here in a looong time. Well I'm building a pc again. I am mostly confused by the different standards there seems to be for PSUs, like ATX (I get this one) and now EPS12V and ATX12V 2.2. They seem to have differing amps for the voltages I pay little attention to, like 3.3v and 5v. I just want to make sure I get the right PSU for my mobo and cpu.

Newegg.com - GIGABYTE GA-EP45T-UD3LR LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards

Newegg.com - Intel Pentium E6300 Wolfdale 2.8GHz 2MB L2 Cache LGA 775 65W Dual-Core Processor - Processors - Desktops

I will also be getting a 9800GT. Been trying to figure out which PSUs work but I can't wrap my head around this math everyone does to calculate amps (History major).

PSU I know will work is - Newegg.com - OCZ Fatal1ty OCZ550FTY 550W ATX12V / EPS12V SLI Ready CrossFire Ready Modular Active PFC Power Supply - Power Supplies
OCZ 550W - I picked it for the high amps on one rail, since I don't understand how to calculate how many amps I can get to the GPU (only one PCI-E port for 9800GT) when there are multiple rails.

But after doing a techimo search I stumbled upon this guy.
Newegg.com - CORSAIR CMPSU-400CX 400W ATX12V V2.2 80 PLUS Certified Compatible with Core i7 Power Supply - Power Supplies
Corsair 400w. My main concern is the varying amps on the rails I never pay attention to. Will my system be ok with that?

Specs will be
motherboard listed
9800GT
Pentium E6300 (might be OC'd, but no volt raising)
1 HDD
1 Optical drive
4 GB (2 x 2GB) DDR3 1600

Again, thanks for the help. I always know where to go for solid help.

pullmyfoot · November 3rd, 2009, 10:21 AM

It will be no problem whatsoever. Good unit and more than enough power for you. You might want to look at a 500W unit maybe if you want some space to spare though. Currently your system will probably do something like 300W at full load.

stroyal · November 3rd, 2009, 10:27 AM

The most important spec is the brand, and you are good on both.
The corsair would probably be enough.
If your video card does not require more than 30 amps.

To get more than 25 amps out of the duel rail, you would have to use a jumper to connect the 2 rails for a total of 550 watts = 38amps@12v.
If I read the total 12v wattage right.

My HD3850 requires 30 amps on the 12v rail and I have a RAID with a 3rd drive for a backup.
Also 3 opticals, and a zip.
I have a Corsair 450 with 33 amps on the 12v rail, and it has plenty of power.

stroyal · November 3rd, 2009, 10:38 AM

Beaten again.

The only other consideration I could add is if your video card uses less than 25amps and you wanted to take advantage of the benefits of the duel rails (If there really is an advantage), you could use the OCZ. If you have to use a jumper it defeats the purpose of multiple rails.

pullmyfoot · November 3rd, 2009, 10:51 AM

johnross2007 · November 3rd, 2009, 11:36 AM

You guys are awesome. I think I'll go with the Corsair 400w. I don't need an extra 100w of headroom. This computer is to be built and sold and to be built as cheaply as possible while still be REALLY reliable. I don't want headaches with customers and I want them to have a product that will last.