Power Supply Information

[Age]

So in my "A Video Upgrade" thread I've been told that I will need a new power supply with any major video card upgrade. That's fine, but I'm curious about power supplies in general. When I read the specs of power supplies I come across terms such as "modular", "12v rail", "amprage", etc.. Now I've always prided myself in being fairly computer-savvy; I know how to navigate and use a system with a certain degree of speed and efficiency, although I probably know little in the big picture. I've been glued to a monitor since I was five (Now seventeen).

But I've never been one known for hardware know-how, so my question is: Can anyone either give me a basic run-down of power supply terminology, do's, don'ts, and anything else important I might need to know? If anyone could simply direct me to a site that gives comprehensive information concerning these all-too-important system components, it'd be greatly appreciated.

If you'd also like to tell me to go and find it all myself, that's okay too.

Help is appreciated, flames are not.

--A

 

[MarcVenice]

12v rail is where the gpu takes its power from, but the cpu/mobo and other things also get there power from the 12v rail. The higher the amperage on the 12v rail the better. For a 'normal' pc, with a powerfull videocard like a 8800gts or gtx, something with at least 30a on the 12v rail is recommended. Back in the days the 5v rail was most important, but nowadays it's the 12v rail that needs the most attention. Modular, theres LOTSA cables to hook everything up, but with a modular power supply you can plug in only the cables you actually need, wonderfull thing.

Why don't you just mention the PSU you have, the videocard you are going to buy, and how much you can spend? Who knows, maybe your PSU is in fact up to the task of running a better videocard.

 

[Age]

I was under the impression that the 12v rails were somehow a part of the PSU itself...

But as to your final point, I'm asking this not for reference on buying the new PSU / card, but for future reference in general. I've been recommended several PSUs and have seen others that have been recommended in threads throughout these boards. But even then, I was running across terminology I wasn't familiar with, thus I asked.

I'm not sure which card I'm going to be getting, but it will probably be either an 8800GTX or 9800 GTS (Either around the release of the 9x series). My current PSU is a mystery to me; all I know are the numbers I provided and that it's an Allied PSU. From what I've read, though, my wattage is going to be lacking - I'm hearing numbers in the upper 400s and beyond, and apparently my PSU is only capable of about 280W, or so I read on the cover.

 

[MarcVenice]

The 12v rails are part of the PSU. Wikipedia will help out http://en.wikipedia.org/wiki/Power_supply_rail

And nowadays it's somewhat save to say you need a qaulity 400w built PSU, from seasonic, doing 30a on the 12v rail(s) or better. 450-500w is somewhat recommended, with at least 30a on the 12v rails, 35a or so should be plenty for a gtx or a 9800, since the latter should be consuming and drawing less energy.

 

[Age]

Alright, I've done some more looking and now I've considered, as someone in my video thread suggested, buying an X1950XT for now and selling it post-9x release. While I'm at it, though, I'm probably going to go ahead and replace my PSU. Now from what I can tell at Newegg, the rail amperage is told from the specs they provide as such:

+3.3V@24A,+5V@24A,+12V1@17A,+12V2@17A,-12V@0 .8A,+5VSB@2.5A
( http://www.newegg.com/Product/...x?Item=N82E16817151034 )

In which case I'm having a hard time finding a PSU capable of +30A on the rails. I might be missing something here; any help on this front is appreciated. :>

 

[MarcVenice]

You don't need 1 rail to do 30a or more. The combined amperage on those 12v1 and 12v2 rails is going to be roughly 30a or so. You can't really add them up, to say it's 34a combined, but it usually comes pretty close. So the PSU you stated is just fine. A videocard doesn't use 30a, but the guesstimate is that a PC with a cpu, 1950xt, motherboard, harddrives etc uses roughly 30a. One rail, the 12v1 rail for example, provides the cpu, motherboard and the ram with the energy they need, the other rail, the 12v2 rail will supply the videocard and the hdd's with power. It's that easy

Oh, and there's cheaper options if you'd like, like this one http://www.newegg.com/Product/...E16817139003&Tpk=450vx

It has 33a on the 12v rail, which is plenty for your needs. My 8800gts runs on a PSU with roughly 30-34a on the 12v rail. Newer gpu's are said to be less powerhungry, so it's all good

 

[mpilchfamily]

This should help you a bit.

http://www.xcpus.com/forums/ca...u-selection-guide.html

And this is a nice little reference list of popular PSUs. The Prices may be out of date though.
http://www.xcpus.com/forums/ca...su-reference-list.html