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Very confusing problem, genius required.

Last response: in Systems
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Anonymous
March 5, 2010 1:26:30 PM

Hi,

I have just put together a new build, but when i booted it up, the case fans would start but slowly, the GPU fan would start, and the PSU fan and processor fan would start, but spin slower than normal. It turns on with the power button, but won't turn off again until i switch it off by the PSU switch.

No video output, no POST or Beeps.

Its a crosshair formula 3, xfx 5850, phenom 2 965, and OCZ 850 GameXstream PSU.

Ive tried everything, plugging everything in in different orders, ensuring things are connected correctly, plugging in bare essentials, e.g. just motherboard, GPU and ram stick.

I tried an older video card, 9800GT (which would seem to boot with, but no video output still) , and a GTX275 which was the same result as the 5850.

I thought it may be either the PSU, or a motherboard fault, but i swapped out the PSU for my flatmates 600w EZcool, and it runs perfectly, and my PSU powers his setup without any problems, so i'm stumped.

So my PSU works fine it seems, and so does the motherboard and components, but when i combine them they won't work. I'm baffled.

Any geniuses out there?
March 5, 2010 9:16:20 PM

I'm confused. Are you saying that your system works fine when using the 600w EZcool PSU?
March 5, 2010 10:09:01 PM

So i guess its ur power supply?
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March 7, 2010 5:57:38 PM

The OCZ PSU has more wattage. It just got the amperage spread out over 4 rails, instead of having a high powered single rail. The problem is when there's a high demand that a single rail can't support.
Anonymous
March 7, 2010 6:44:05 PM

aford10 said:
The OCZ PSU has more wattage. It just got the amperage spread out over 4 rails, instead of having a high powered single rail. The problem is when there's a high demand that a single rail can't support.


Ok thanks, how do you know when your buying a motherboard if the power supply will power it?

Also sorry i know very little, but trying to learn, why is 25amps on one rail able to power it, but 4x15 isnt?
March 7, 2010 9:39:48 PM

It's not the motherboard as much as it's the video card, that the PSU has to power. The video card is the largest draw of power.

That's why it's important to look at the number and size of the rails before selecting a PSU.

The problem with the multiple rails, is it spreads the amps out too thin in this case. The OCZ has more amps overall, but they're spread over the 4 rails. The video card needs more on the 12V.
Anonymous
March 8, 2010 1:05:23 AM

aford10 said:
It's not the motherboard as much as it's the video card, that the PSU has to power. The video card is the largest draw of power.

That's why it's important to look at the number and size of the rails before selecting a PSU.

The problem with the multiple rails, is it spreads the amps out too thin in this case. The OCZ has more amps overall, but they're spread over the 4 rails. The video card needs more on the 12V.



See this is another reason i find the whole scenario confusing, i had the same video card in my old setup, gigabyte motherboard q6600 etc, and the PSU had no problem powering it :S
March 8, 2010 1:41:09 AM

If it was powering the old system, there was very little overhead. The new hardware is likely just a little too much.
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