Built my first PC - it turns off after less than a minute

Last night I built a PC for the first time. I think I was pretty methodical and made all the right connections. When I turn on the computer, it seems like everything is fine. It sees the graphics card, the CPU, the RAM, and both hard drives. The dvd drive and the keyboard both work. The 4 case fans all come on. The CPU fan and the power supply fan both come on. The interior blue lights come on.

Then, after about 40 seconds, it just shuts off. No beeping, no error message... it just turns off. It doesn't matter what it's doing at the time. If I hit delete to go into the bios, while I'm in there it will just turn off. Or if I let it boot from the Vista CD, it'll be on a screen with a progress bar saying "Windows is loading files", it will get about a third of the way through the progress bar, and then shut off.

My biggest concern is that everything seems to be working perfectly and then it shuts down, and I don't know how I will find the problem. Any help you can offer would be greatly appreciated.

Someone on CNET felt it's because I hadn't applied heatsink compound, but I've done that now, and it still shuts down.

My specs are as follows:

Case: Antec Nine Hundred
Motherboard: XFX nForce 780i SLI
CPU: Core 2 Extreme Quad-Core QX9650
RAM: Patriot Extreme Performance 1066mhz PC2-8500 (4 x 1gb)
Power Supply: Antec TruePower Quattro TPQ-1000
Graphics Card: XFX GeForce 8800 GTX
Hard Drive: WD Raptor X 150gb
Hard Drive: WD Velociraptor 300gb
DVD Drive: LG SATA Super Multi DVD Rewriter 20x
Sound Card: Sound Blaster X-Fi Xtreme Gamer
Monitor: LG L227WTG-PF 22" LCD
Keyboard: Logitech G11
Mouse: Logitech MX 518

 

make sure cpu fan is plugged in on cpu fan header. Also let it get into bios and check pc health for temps.(should be able to access in 40 seconds hopefully) if all else fails take it down to minimum (vga, cpu, 1 stick of ram, and a hdd) and see if it stays on (try with different sticks of ram), also make sure all stand offs for board are in the right spot. Let us know what you find.

 

This also happened to me when I built my first PC and it turned out that I didn't quite get the heatsink flat to the processor, so the system would shut down to protect it from over heating.

 

Yup.... it's a heatsink/CPU problem. The CPU is getting too hot. I have seen first-time builders overlook some things when it comes CPU heat sinks. I have seen the plastic cover that comes on many heat sinks actually left on the heat sink when it was put on the CPU. I have seen heat sinks just kind of set on the CPU and not tightened down so they basically made no contact. I have seen both the lack of thermal paste and the overuse of thermal paste, both can cause overheating. One guy used the whole tube and there was a huge puddle of paste all around the CPU socket. Also, check to be sure the fan is plugged in to the proper header with the correct alignment (they're usually 'keyed' to prevent plugging them in backward). You can also just go into the BIOS and go straight to the hardware monitor/PC health section and watch the CPU temp; if you see it increasing rapidly to over 55/60c (it's probably getting much hotter than that) then you know for sure that it's a thermal issue. ibbonkers makes a good point about the standoffs; many first time builders mistakenly put a standoff in each available spot on the motheboard and not only in the spots where they should go. This means that several of them will be in the wrong places causing the motherboard to short out and can sometimes cause permanent damage to a system board. Usually when standoffs are in the wrong place, the PC will not power on at all, or powers on for only a second or two then shuts down right away, so this is probably not the situation here.

 

Wow! It looks like the consensus is the heatsink. I completely believe you, but at the same time, I feel like I followed all the directions for applying the compound and attaching the heatsink. It seems fairly secure. And yes, it's plugged into the CPU fan connector designated by the motherboard instructions. It is keyed, and it's in correctly. Also, the case is clear on one side, and I can see that the fan comes on.

I'll probably end up having someone else take a look at it. I will post here to let you know how it goes.

 

Did you try this? If so, what did you see?

 

Ok, here's the update.

You all were indeed correct that the issue was the heatsink. I took the PC to a local computer store and he determined that half of one of the plastic prongs, on one of the four posts that you lock into the motherboard, was bent. So it did not go completely into its hole, and although that corner of the heatsink was secured in place by the other half of the prong, it was not all the way down, due to the bent half.

He took the heatsink out, straighten the bent half, put it back in and the shutdown problem was fixed.

However! This morning, I sat down to install windows, and it would only go so far, and then it would give me a blue screen error message. I called the guy and he told me to take out 2 gb of my 4 gb of ram. I did that and still got the blue screen - so I took the PC back to him.

He ran a diagnostic test on my ram, and 2 of the sticks were getting errors, 1 stick was fine and we never tested the 4th stick, since I had already decided I was returning them all. He gave me a copy of the memory diagnostic test. I returned the Patriot ram and got 4 x 1gb of Kingston Hyper X 1066mhz DDR2 PC2-8500.

All of the ram just passed the diagnostic test and vista is installing!

All of your assistance was extremely helpful. The tech charged me a nominal fee because you helped me tell him exactly what the issue was, so he looked directly at the heatsink and saw the problem, and didn't spend time searching for the issue. Thank you all again!