First, thanks for reading this and all help is appreciated. I built this computer back in late April and it's been working fine until last night. I still use my old one until this one is completely loaded with the programs I need so it’s not used every day. The last time I used it, the day before, it worked great as always and shut down normally. I noticed the problem after I had unplugged it from the UPS and plugged it into a Kill A Watt wattmeter to see what kind of wattage it took to run it. It wouldn't turn on at all. I then replugged it into the UPS and nothing. I had used the wattmeter with other things that day and they all worked fine. I then changed power cords twice and even tried a different outlet but nothing.
After eliminating the power source and cord I then started to check the components. I tested the momentary on switch w/a Vom and it was working most of the time. To work around this I then briefly shorted the 2 terminals it attached to and nothing. This should have eliminated the switch as the problem. I then removed the MB power cable and used a wire to cross the green and 1 black wire. The attached case fans and video card fan came on but can't be sure the power output is in specs nor if the output to the MB was working, only those to the fans and the video card which is powered directly from the PS(power supply). Not sure what to try next. Could it still be the PS or maybe the MB or CPU? It's worked perfectly since it was built until I unplugged it from the UPS. There’s been no storms or other electronics problems here. The weather and temp are the same and no big changes there. There’s been no new components added. It’s been a sweet system until this. I’m at a loss as this point and hope someone else can see what I’m not seeing, or have an idea as to where to start on this problem. I know a PS tester would tell me if the PS is powering up but not sure if they tell you if it’s the correct amount of voltage which might cause this so not sure if I should purchase one or not. Replacing the PS is usually the first course but it would be wasting $ and time if it’s the MB. Can anyone out there tell me how to completely eliminate either of these 2 w/o replacing them one at a time since the power switch was eliminated?
The computer stats are:
Cooler Master mid-tower case
AMD Phenom II 1090T 6 Core CPU
GIGABYTE GA-890GPA-UD3H MB
APOWER Sata Euro 12v 750 watt PS
Windows 7 Ultimate OS
8gb Corsair Ram w/dual fan cooling tower
Sapphire Vapor-X Radeon HD 5770 860MHZ 1GB Video Card
Samsung 500gb HD
Sony 24x Light Scribe CD/DVD W/RW Drive
Rolli thanks for the reply. I had already checked the PSU of the older computer and it's not capable of powering up the new board even though it's rated for 450watts. The secondary MB cable only has 4 outputs while the new one requires 8 pins. I did follow the link you gave and performed the powered up Vom testing of the MB main cable. All wires put out the stated voltages as given for the colors as noted including the one putting out -12 volts. I also checked the secondary cable and each pair was putting out the same voltage as the others. Of course these values weren't under load, but I'm more hesitant to try and check the voltage from the backside of the MB while it's live. I am thinking it may be the MB, but I can't understand why it would just up and die like that without any kind of warning. I remember when building it I had forgotten the 2nd smaller MB cable and it wouldn't boot up like this, but then saw it wasn't attached and once in place it booted properly when started. This is not the case this time. As I said, it's been working fine for 5 months until I went to turn it on and it just wouldn't start or even try.
Any more suggestions? I don't have a 2nd MB to swap out and check the CPU and PSU. The MB and CPU have 3 years warranty, but I want to make sure what the problem is before I try to get warrany service replacements, especially if it's for a part that's not the problem.