First build, powers off on first boot.

[Thelps]

Hi there. I just moments ago finished assembling my first PC. However, when I start it up for the first time it appears to begin fine, with the graphics card being detected, no error beeps from the mobo and the motherboard startup screen appearing, the problem is, within 30 seconds to 2 minutes of power-on the PC randomly turns itself off. The motherboard LEDs remain on after the power off but the PC itself turns off. This happens every time I start up. Perhaps it's a wiring problem since this is the first time I have built a machine? Maybe a PSU problem? I'm really in the dark here and would appreciate help from anyone who is familiar with this kind of issue, or any of the components I have used to build the machine, especially the motherboard.

My PC:
Mobo: ASUS Striker Extreme
Case: Antec P180
PSU: Silencer 750w Quad
CPU: Intel QX6700 Kentsfield (Quad Core)
Ram: 2x 1GB PC6400 DDR, installed in the blue slots (Dual Channel)
Hard Drive: Western Digital Raptor 150GB 10,000 RPM
Graphics Card: XFX GeForce 8800 GTX

As I said, boots fine, but either during initial boot, or while I examine the BIOS settings, or even during attempted install of Windows XP Pro the PC will just turn itself off. I doubt it's a specific component issue since the PC detects all connected components. Any advice on wiring pitfalls, hardware issues, or motherboard settings I'm not aware of that could cause this problem would be very appreciated, as well as anything else that comes to mind, especially with people familiar with such a problem. Thanks in advance.

[ski]

A possible cause is the CPU overheating. You can confirm this by going into BIOS, and observing the CPU's temperature. If the 'CPU Shutdown Temperature' is enabled, and the CPU temperature exceeds the Shutdown Temperature setting, then you have the cause.
If that's the case, then make sure the CPU's fan is running, it's correctly oriented with the air blowing into the CPU's heatsink fins, the heatsink is firmly secured, and thermal compound was applied between the heatsink and the CPU's die. If the heatsink came supplied with a thermal pad, then make sure the plastic cover was removed from the thermal pad.

[Thelps]

I'm using the standard Intel Heatsink/Fan assembly supplied with my CPU.

It seems CPU temperature is the problem. Checking the BIOS before the PC inevitably shuts down) shows the CPU temperature at 90 degrees C and rising. The system shuts down once it reaches anything over 95 C. I've remounted the CPU cooler (in case it wasn't correctly mounted last time) but now when I start the PC all the fans spin up and the mobo lights up but nothing happens on the screen. I'm receiving the message 'CPU Init' from the motherboard LCD diagnostic screen. Of course, the manual doesn't contain the meanings/causes of the messages from the LCD screen so I'll have to check around online.

I suppose at this point I have to consider whether the CPU has fried itself or not, since 'CPU Init' probably means the mobo can't get past initialising the CPU. Is 95C a sufficient temperature to fry a CPU, given it's only ever been on for no longer than 2 minutes at the absolute maximum?

[ski]

It sure sounds like the CPU is toast. 90 C is plenty hot enough to damage it. And a 95 C CPU temperature shutdown setting in way too high. It should be set for around 65-70 C.
Now the question is why did it overheat? Did you do everything I mentioned in my 1st post?

[Thelps]

Everything mentioned in your first post was done, except that no thermal compound was supplied with the CPU (bought brand new, Intel factory-sealed box) so none was applied. I have since ordered some to see if I can coax life out of it yet.

The temperature shutdown level was the factory default set by the motherboard. I never got the chance to configure the BIOS. I don't know the true temperature shutdown cutoff since the PC was never stable long enough for me to find out via the BIOS. Like I said, it would self-shutdown anywhere between 30-120 seconds after startup).

Once the thermal paste compound arrives in the mail I'll give the rig a shot, with the compound applied. Until then I'm not going to turn the machine on for fear of putting it at further risk.

[Thelps]

A couple of (happy) updates: Firstly, I tried the system again after having meticulously cleaned the IHS and heatsink/fan assembly connectors. The PC now boots to the BIOS with a recorded average temperature of 55C with the case open and 60C with it closed. This is without the use of any thermal paste. Obviously these are somewhat high temperatures for a processor that's under effectively zero, but a HUGE improvement over burnout-pushing levels of 95C. With thermal paste things can only get better. Also, it confirms the processor isn't dead, which is a huge load off my shoulders.

[ski]

Glad to hear the good news.
The system should not be run without any thermal compound applied to the CPU and its heatsink, since local hotspots can develop on the CPU die that can fry it even though the CPU temperature in BIOS indicates a safe 60 C +/-.

"Firstly, I tried the system again after having meticulously cleaned the IHS and heatsink/fan assembly connectors."
Does this mean that the heatsink was not firmly secured to the MB?

[Thelps]

I refitted the heatsink/fan assembly after cleaning the processor IHS, so it's possible it wasn't properly fitted the last time. This is the third time I refit the assembly so it's quite possible it wasn't stable the other two times. I'll continue testing and trying to install XP Pro once the thermal compound arrives.

[ski]

OK, sounds good.
BTW, some CPU heatsinks can be a bear to properly secure.

[Thelps]

I'm using the stock Intel heatsink supplied with the processor. The clips require a somewhat worrying amount of pressure before the reassuring click that shows it's secured. The motherboard creaks and complains during the installation. Maybe that contributed to me being overly cautious the first two times I fitted it.

[ski]

Been there, done that. And I'm not sure that installing those heatsinks on subsequent custom builds gets any easier.

[Hagar]

...The motherboard creaks and complains during the installation. ...
Avoid putting stress on the MB, it might develop fine cracks in the traces (= dead MB).
I always fit the heatsink with the MB laying flat on the table, not when installed in the case.

[Thelps]

The way the heatsink is designed is so that the clips extend below the surface of the motherboard and clip into place like that. Because of that, the motherboard has to be suspended off a flat surface to make installation of the heatsink possible.

[Thelps]

Applied the Arctic Silver 5. The CPU temp at the BIOS now displays as ~37C so it's at a stable temperature now. Some other problems are no evident though. After the BIOS loading screen appears the PC doesn't read the CD/DVD ROM drive, it just pauses at a black screen and waits. This means I can't install any OS.

I have the DVD drive set to the master drive. It's the only input drive installed on the system. Apart from that there's only one hard drive installed. Any idea what I can do about the problem?

[ski]

See if the drive is recognized in BIOS. If it is, then insert the O/S CD, set the system to boot from the DVD drive in BIOS, save the change, and install the O/S.
If the drive is not recognized in BIOS, then make sure the IDE channels are enabled in BIOS.
If they are, then connect the drive as Slave or CS.
If no luck, then connect the drive to the other IDE channel.
If no luck, then install a different known working IDE cable.
If no luck, then the drive may be bad. See if it's recognized on another system, or try a different drive on your system.