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Save me from this headache. (PSU Selection)

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December 7, 2006 9:37:57 AM

I'm looking to build a new pc in the near future, and I could really use some advice in selecting a psu. I realize that hardware has become more greedy and demanding, but I never thought choosing a simple power supply would ever be this difficult. I'll try and explain to you guys what I've got my eyes set on in terms of hardware.

This will be a gaming computer, but before anyone starts salivating and throwing out reccomendations for parts x and y.. There won't be any overclocking done at all. There won't be any additional cooling systems, extra fans, etc. I don't intend to make a "beast" of a rig. I just want something simple that will allow the "not so (anymore)" hardcore gamer to play the newer releases and have a bit of fun. I've decided to go with a E6600 for the cpu, and a 7900gt video card to start. The video card will certainly be upgraded later on down the road, so please keep this in mind for the psu. Other than that, I'll have two internal HD and optical drives.. a few usb devices here and there. Nothing big.

I read pages upon pages of posts, but I still can't find the answer.. and the guides are like moonspeak to me. :wink: First of all, the amps of the 12v rails is lost on me. How many rails should I be looking for? How many amps do I need for what I've got picked out? How is the power distributed across each one? I know I've read that many of the new video cards require something around 29 amps? Does this mean that each individual 12v rail must be listed at that or greater for it to function? Or if say... I have a psu that lists 4 rails at 18 amps, does it divert power to that one rail in order to supply the card with enough juice?

I suppose you don't have to try and explain it to me. But I would like some suggestions on what to buy.
December 7, 2006 11:29:48 AM

Basically, buy at least a 500W PSU, and you'll be fine from a name brand supplier. Don't worry about rails so much, but the combined wattage the 12V can push out. When a gfx card says they recommend 29 amps or something, that's total system amperage, not just for the card.

Either way, 18A on multiple 12V rail's is fairly standard. And no, I'm too lazy to suggest PSU's.
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a b ) Power supply
December 7, 2006 11:51:42 AM

Let me restate what TabrisDarkPeace said and possibly make this easier for you. Let's say you are going to upgrade your video card from the 7900GT to one of the 8800 series - Go to the nvidia site which TabrisDarkPeace has listed, and select a supported PS for what you may upgrade to.

The reason I suggest this is that these new cards are very power hungry - and if my perception is correct - the next versions will possibly be the same or slightly less power hungry. Selecting a currently supported PS will allow you to power everything you currently have, and give you flexibility for the future. Nvidia has already figured out what will be needed (amp wise) so go to the site and find something that will fit your current upgrade plans.

Cheers.
a b ) Power supply
December 7, 2006 3:59:09 PM

Quote:
Basically, buy at least a 500W PSU, and you'll be fine from a name brand supplier.


In general I agree. Since you will not be overclocking your current power needs will be pretty low. The E6600 only consumes 52w of power under full load. The 7900GT only consumes about 49w of power. That's a total of 101w on the 12v rail under full load. Toss in another 16w for every hard drive and DVD drive.

Since you are not a "hardcore gamer" as you said, then it's probably very unlikely you will be stepping up to the 8800GTX (nVidia's flagship card) which draws 146w from the 12 volt rail under full load. That works out to be about 12.17 amps (146w / 12v). The nVidia's recommendation is either a 450w or 500w PSU for this GPU; I don't recall.

According to an Anandtech.com article some time earlier this year, "reliable sources" said that the second generation of DX10 GPUs will be less power hungry than the first generation. So the "8900GTX" should draw less than 146w.

A good nambrand 500w PSU should cost you around $80 - $130. Recommend namebrands includes: Fortron (FSP Group), Antec, Silverstone, Hiper, Seasonic, and Enermax.

CPU Power Consumption Chart

7900GT Power Consumption

8800GTX Power Consumption
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