nForce 790i Ultra SLI power problem

Xfx79u / Xfx nforce 790i ultra 3-w...
July 23, 2009 at 10:30:12
Specs: Windows Vista SP1
I just put together a new computer with the nForce mainboard, and it seems to be working great, except after about 30 seconds of me turning it on, it shuts off all on it's own... I have a 1200W power supply and 2 nVidia 9800 GT video cards also installed, along with a 3.0GHz intel processor. WHY WON'T MY COMPUTER STAY POWERED ON?! Someone please help...

See More: nForce 790i Ultra SLI power problem

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#1
July 23, 2009 at 10:34:26
Exactly which 1200w psu do you have?

Have you checked cpu temps in BIOS?

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#2
July 23, 2009 at 10:38:43
I have a coolmax power supply and I haven't been able to check hardly anything because it won't stay powered on long enough for me to look too far in the BIOS. I don't think cooling is a problem though. I have 5 fans running in the tower (not including the processor fan or the 2 video card fans)

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#3
July 23, 2009 at 11:13:39
Improper application of thermal paste to the CPU/heatsink can cause that problem. Using too much is a common cause.

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Related Solutions

#4
July 23, 2009 at 11:30:59
It still sounds like the cpu is overheating. What did you use for heatsink compound? Is the heatsink properly attached to the cpu? Did you use the cooler that came with the cpu?

Take a minute to read the label on the psu and let us know the amps on the +12v rail(s). It's important information.

The 5 fans you're running don't have anything to do with this problem...we can talk about that kind of overkill later.

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#5
July 23, 2009 at 11:41:56
I agree with aegis1...check the heatsink installation. Find your CPU at the following site & make sure you've applied the paste as described. If you did it differently, remove the heatsink & redo it:

http://www.arcticsilver.com/ins_rou...

"I have a 1200W power supply"..."I have a coolmax power supply"

I'm a big proponent of buying decent quailty, name brand power supplies, but that's a lot of money for a PSU:

http://www.newegg.com/Product/Produ...

One of the problems with the multi +12v rail design is that you have to "hand balance" the load so that one rail doesn't become overloaded while another is left unused. OCZ makes it easy by putting a list on the label (lower left):

http://www.legitreviews.com/images/...


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#6
July 23, 2009 at 13:36:25
I thank you guys for the help. When I installed the CPU, it had some kind of compound on it already, but didn't come with any that I could apply myself on top if it. there is a little light on my mainboard that says if the CPU is overheating, and it has come on before, but only a couple of times. Also there is a little diagnostic meter on the mainboard that displays codes and I get a code "7F" which the mainboard manual says it's a "POST error check" and the description of the fault is "Check POST error and display them and ask for user intervention". I must say though, that I have never built my own computer before so maybe I have some little wire connected wrong or somthing. I have compared the new computer with the computer I am usuing now (which is factory built) and I can't find anything wrong, although this new computer has a lot more tiny 1 pin and 2 pin wires that don't exsist on my old computer (i.e. the power and reset buttons, 1,000,000 differenet SATA places to plug cables). Could that be an explination? I have followed the users guide to install everything, so I'm not too sure what's going on. Thanks for your help again.

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#7
July 24, 2009 at 06:01:55
"there is a little light on my mainboard that says if the CPU is overheating, and it has come on before, but only a couple of times"

If the heatsink/fan is properly installed, the light should NEVER come on. Double check the installation.

"Check POST error and display them and ask for user intervention"

Check your keyboard connection. If it's USB, try PS/2 & make sure to plug into the keyboard port, not the mouse port.

You didn't comment on the power supply or whether you properly balanced the loading on the +12v rail(s)? Temporarily pull one of the video cards to lighten the load.


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