This is my first post and it is kinda long. To help with readability, I divided it into 2 parts: 1) the bare essentials, followed by 2) more depth and history "Long Version". My PC details are at the end.
In my efforts to diagnose my PC start-up problem, I removed almost everything inside the PC. Only the motherboard, CPU, CPU fan, the 3 system fans, front header connections, PSU, and the case remain together. I press the ON/OFF button, next all the phase lights inside the PC light up and the CPU and system fans also turn on ... for 10 secs, then these shut down for 5 secs, start up for 10 secs, ad nauseum! The monitor starts off blank and remains blank (black) no colour, text whatever, never gets to POST screen. Pressing the ON/OFF button has no effect.
Does this cycling indicate a problem with the mobo or CPU? I tested the PSU and it appears fine (See Long Version for detail).
If the components were all fine, what should I expect when I turn the power on?
If all the components were fine, my thought is that the power LEDs should light and fans start, without cycling. I think there is a problem with either the mobo or CPU but could it be something else I am familiar with PCs but am not really technically proficient, I thought it would be helpful to ask for advice from others more knowledgeable than I.
This actually started March 2013. System logs showed a "major event" happened in March. The PC powered on intermittently. Took me a while to figure out the PSU was a problem. Bought a new 720v CoolerMaster.and installed in early September (I couldn't decide what to get!!). Powered on reliably with new PSU but...
PC would go through POST, Microsoft start-up screen appeared, screen went black, stayed black. (In the good ol' days, the black screen would take about 10 secs then the account log-on screen would appear (I have 2 accounts on my PC)). Pressing the ON/OFF button was ineffective. Pressing the reset button, I could boot up into Start-up Repair.
Running Start-up Repair options: the Restore only found the "windows.old" folder, the Memory Test was fine. Startup repair details usually indicated a bad patch, all the other tested parameters were OK.
I researched various sites for possible solutions and fixes ... did complete system virus scan, scanned with MBAR, installed new drivers, tried rolling back a bad patch (DISM), checked BIOS settings (toggled IDE/AHCI SATA controller), tried fixing Master Boot Record, finally did a Repair Install of Windows 7 Professional. Nothing I tried has worked. Just recently I read about replacing the CMOS battery; last week, I bought and installed a new battery. I turned the PC on and it booted up right into the account log-on screen!!
I was amazed that a lowly battery could have such an impact. With bated breath, I shut down the PC and started up again. The computer started up for a few seconds, then went off, then went on again, then went off, etc. until I turned off the power bar (pressing ON/OFF button had no effect). More specifically, the phase LEDs and fans come on for 10 secs, the lights and fans go off for 5 secs, then this continues in the same synchronicity until I turn off the power.
I have gradually removed the innards of my PC to see if I could get a beep code or any sound whatever or get the cycling to stop. I am now down to pretty much the bare essentials (as described above). This morning it still does the exact same cycling. An hour ago, I tested the PSU with my PSU tester. The results were dead on or within range (the 12v1 reading being 11.5 and the PG was 360ms). I also tested the PSU with the paperclip and the fans started running. So I don't think it is the PSU. I suppose it could be the front header but it didn't seem likely.
With this stripped down system, I THINK the fans OUGHT to go on and stay on, just stay running, until I cut the power. I think the cycling on & off confirms that I have a mobo and/or CPU problem?
Thanks for taking the time to look at this. Your thoughts are very much appreciated.
SPECS: I built this in 2009 based on a Tech Report system build
Motherboard: Gigabyte EA-EP45-DSR3
CPU: Intel Core2 Quad CPU Q9550 @2.83 GHz
CPU fan: Zalman CNPS9500A
PSU: CoolerMaster Silent Pro 720W (RS720-SPM2D3-US)
RAM: 4G Kingston DDR2 (KVR800D2N5K2/4G i.e. 2 sticks, each 2G)
Hard Drives: 2 x Western Digital Caviar SE16 Sata (2 drives, 1GB each)
Network Adapters: 2 x Realtek 8111C (10/100/1000 Mbit)
Graphics: EVGA NVidia GeForce 9800 GTX/9800 GTX+
Sound: Asus Xonar D2X
Blu-ray/DVD-ROM: LG GGC-H20L
Mouse: Logitech G5
Keyboard: Leopold FC500RR/AB
Monitor: SyncMaster 2253BW
UPS: APC BACK-UPS ES750)
Case: Antec P182
OS: Windows 7 Professional with SP1