X48 Mobo Computer when switched on repeatedly reboots and sometimes works fine

Question

Hi there Before I go on any further, here are my system specs
Aerocool 650W PSU
MSI X48C Motherboard
Intel Duo Core2 E8600
4GB (2X2GB Kit) Crucial Ballastix Tracer Ram
XFX 9800GTX Black Edition 512MB
Creative X-Fi Gamers Edition
Maxtor 500GB SATAII
Maxtor 125GB SATA
Maxtor 125GB IDE
LG DVD Burner
My problem is this. Whenever I switch on the computer, at times, it'll run fine. At other times, it'll not even boot into the POST screen and there will be a blank screen for about 5-10 seconds before the computer switches off on its own, before switching back on again. When it does switch back on again, it may or may not boot into POST. At times it does, at other times it doesn't. My BIOS is the newest available, Version 7.0, and all settings ini BIOS are set to default.
However, when the computer manages to boot up, it runs perfectly. I've stress-tested it by leaving it on the whole night, running software tests on it, and it works perfectly... until I decide to soft-reboot the computer and it acts up again. Can anyone help? Thanks!

Answer 1

I had the same problems that the top poster, Startrail85, describes. I solved my problem and want to share my solution.
In brief: short circuiting from my aftermarket graphics card cooler touching one of the graphics card ram sinks was fixed by removing the ram sink.
In detail:
I too have a X48 motherboard. After solving the problem of being unable to boot the board at all with a Q9550 CPU and a BIOS version 7.0 everything was fine (by booting with a cheap CPU temporarily installed and flashing to BIOS V7.3). It would boot up first time, every time. This was so for about a month. Then I started to have the same problems that Startrail85 describes.
Sometimes turning the computer on in the morning would lead to multiple rebooting, mostly more than two reboots, without reaching the POST screen. Sometimes I would let it reboot many times and on perhaps the sixth or seventh time it would finally go through POST and into Windows. Once in Windows everything was fine. On rare occasions when turning the computer on in the morning it would boot first time. I could circumvent a multiple boot process by holding the power button done during one or two of the reboot cycles. On the third reboot, or thereabouts, it would boot OK, through to Windows. If I rebooted the computer after it had been on for some while it would reboot OK.
So the problem was frustrating and difficult to test for. I was developing more hate for MSI.
Thanks to Fontane's tip off that he or she had a "cold boot problem caused by my 9600GT"  I removed my second graphics card which, by coincidence, is a 9600GT. The booting problem went away! That's a job only half done because I need the second graphics card in order to have three screens. So I was trying to come up with a hypothesis to test for: 9600GT and X48 simply cannot play nicely?; PCIe setting in the BIOS needs incorrect?; Faulty 9600GT?; New bios for the 9600GT?; Fundamentally flawed design in the 9600GT?
I was shifting the hate toward NVIDIA.
Holding the 9600GT in my hand while allowing different hypotheses to swirl I recalled a basic suggestion from these forums: make sure there is no short circuiting, that no pieces of metal are touching where they should not. Low and behold the aftermarket graphics card cooler that I installed myself, a Thermalright T-Rad^2, was touching one of the ram sinks (that come with the T-Rad^2 and you install).
I removed the RAM sink, reinstalled the 9600GT, and the boot problem is now gone and everything is fantastic. Everytime I power on it boots the first time. None of the double/fake booting that some have mentioned.
Now the hate is properly directed toward myself, the cause of the problem.