Vid card - PSU compatibility?

[Don]

I'm building my first PC and am stumped at the moment. I just purchased a Corsair HX620W modular PSU which I thought was WAY more than enough power for my purposes (I want to exercise the new Vista OS and time some Fortran math algorithms, my hobby). Most of the other PSUs in the store had less power than this one. I also have an Intel DX48BT2 motherboard and an E8400 cpu, and will be purchasing 2Gb of DDR3 memory (1333 MHz) and a pair of Seagate Barracuda 320Gb hard drives.

PROBLEM: I was going to buy an Evga 8600 GTS 512Mb video card in Fry's until I read on the box that it required 400 watts of power (that seems okay) and a "minimum of 26 amps on THE +12 volt rail." My PSU specs list only 18 amps on each of THREE +12 volt rails under max load. Anybody know how I can determine if my PSU can handle this video card? I can't believe 620 watts wouldn't be enough. I would be connecting one PCIe power cable from one rail in the PSU to the video card. Am I missing something here? I emailed evga and corsair last week and got no response. I'm reluctant to plunge ahead and risk damaging something. Any help would be appreciated. Maybe an 850w PSU with one +12v rail would be a better choice.

I have three books on building PCs (2006, 2006, 2008) and haven't found anything about this.

I am now interested in the EN9600GT card, which probably has the same power requirement.

Don

 

[madmat]

Don, as Douglas Adams has famously said "Don't panic". When they say "26A" or what have you they're talking about 26 amps combined on all the 12V rails not a single 26 amp 12V rail or a 26A rail in a multi rail PSU. You generally won't find many multi rail PSU's with 26A on any one rail as multi rails are part of the ATX 2.0 spec which was co-penned by Intel. The reason is that ATX 2.0 calls for multiple rails of 20A and/or less. This is a safety thing to help prevent pushing too much power through a single connector in the event of a near short which could otherwise cause an electrical fire.

Now, just for your gratification the HX620 is advertised as a multiple rail PSU when in reality it is a single rail unit delivering a staggering 50A. By the by, just so you know, rail totals aren't additive on multi rail PSU's. You have a per rail maximum of 18A in your case (but not really since you have a single rail unit but it's a good example) or a total maximum of 600W which equates to 600W divided by 12V for a total of 50 amps.

Anyways, I've seen guys running OC'ed core 2 duos with SLI'd 8800GTX's on that PSU so it's got way more power than you'll need.

 

[Merlin]

Welcome to the forums. Don,

Sounds like a great system in the process.
I agree with Mat here on these PSU numbers.
Also you have a great CPU there, you'll have fun with that one.
The 9700LED Zalman cooler does a great job cooling that CPU

After you get everything put together and up and running, You'll say that it wasn't that hard.
So stick around techgage, if you have any other questions just ask, there quite a few others that build serveral machines a year And some that even modify their systems and cases.

:techgage::techgage: Merlin :techgage::techgage:

 

[Don]

Thanks Mat and Merlin,

You've illuminated a dark area (PSU) for me. Too bad the PSU makers don't include a bit more of this type info in their User Manuals. I guess printing in seven languages makes them reluctant to do that.

Yes, I've heard Zalman makes superb coolers.

Don

 

[Merlin]

Thanks Mat and Merlin,

You've illuminated a dark area (PSU) for me. Too bad the PSU makers don't include a bit more of this type info in their User Manuals. I guess printing in seven languages makes them reluctant to do that.

Yes, I've heard Zalman makes superb coolers.

Don

LOL.... I guess that is why there are forums.
People coming togther to share experiences in the computer field

:techgage::techgage: Merlin :techgage::techgage: