I built this computer about a year ago now (Jan 2010) as a gaming rig. All new components (except for 1 HD). Some changed since new and all are listed... I am running windows 7 Home OEM edition and has had a fresh install including re-format during initial build and once since.
-Gigabyte GA-790FXTA-UD5 Bios updated to F3j, optimised settings, no overclocks, ram re-configured to manufacturers specs....see below
-Kingston HyperX DDR3-1333 KHX1333C7D3K2/4G (2 sticks 2GB each) both installed in proper slots closest to CPU. Set to 7-7-7-20 1T at 1.710 volts
-1st CPU AMD Phenom II X3 705e not over clocked or over volted then upgraded to (Oct 2010) AMD Phenom II 955 revision RB-C3. No overclocks or over voltages.
-Initial build, Sapphire HD5770, added Sapphire HD5770 CFX 3 months later, upgraded to Sapphire HD 6970 and removed HD5770's Jan 2011 5770's ran stock, the HD6970 has the TDP increased 10% in catalyst.
-Initial Build Xion powerreal 1000watt, upgraded to an Antec truepower quattro 850 watt 4 days ago
-2 western digital Black edition 640 GB harddrives (less than a year old) and one Western digital caviar 320 GB HD about 3 years old. Initial build: Primary drive 320 GB and 2x 640GB raid 0. Now 640GB primary and 640GB and 320GB secondary ( included format and re-install of windows)
-coolermaster Hyper n520 CPU cooler (re-seated the heatsink + thermal paste a few times in the past year.)
-LG DVD burner
-NZXT 5 fan automatic speed controller (Molex cable powered)
-Multi card reader (PSU FDD power connector)
-Cooling fans: 2x92mm on CPU cooler (motherboard powered), 1x80mm LED PSU powered, 2x120mm LED fans 1x Motherboard powered 1x fan controller powered, 5x140mm LED fans 1x motherboard powered 4x fan controller powered.
-Dlink wireless adapter
besides wireless keyboard mouse and printer, no other USB Loads.
The problem I am having is at random times during inital cold power-up, resume from hybrid stand-by or windows doing a restart, the computer will shut down. More specifically, any time the power is already off (ie standby or cold start) the fans and power lights come on for a split second then turn off. The LED's on the motherboard remain on, but the system is not booting...no beeps (the speaker is installed on the motherboard and it works), no hd's running, monitors in powersave. During a windows restart, once it gets to the black screen just before the info comes up to display POST the computer shuts off. It always happens before the POST screen even comes up. If I press the power/reset button, nothing happens, if I hit the power/reset button on the mother board nothing happens. The Mother board is recieveing power because the lights on the buttons are lit. I grabbed my multi-meter one day and tested the green wire for voltage whilst the system was having "it's problem" and found 4.9v. I tried the power/reset buttons and nothing happens to that voltage on the green wire. If I jump that green wire to the case or black wire, the system begins to power up; as soon as I unhook it from ground it shuts off immediately. By turning off the PSU power switch and waiting for the motherboard lights to extinguish then turning the PSU back on, it starts up fine and runs completly normally for sometimes months, sometimes an hour until either stand-by, cold start or restart. Has never powered off while I was actively using the machine. I checked the motherboard screws to make sure they are all there and tight, and there are no extra stand-off's in behind. Very random problem and running out of the case could have the machine apart for months. No weird noises are heard any time either.
I am stumped. It's been happening since I built the machine (which is why I listed initial parts above) but it doesn't happen often at all. It happened a few times right after I built the machine then nothing for months, then it would happen again, once or twice then go on for a few more months. It has gone about a month or so now without a hitch and recently happened twice in an hour during the new vid card install as I was removing the old HD 5770's/drivers and installing the HD6970. I can not for the life of me re-produce the problem and doesn't seem to be tied to any installs or hardware changes. I just installed the NEW ANTEC power supply 4 days ago and it has happened once since the new power supply. I was almost sure it was the PSU prior to this new one because it was a cheapo brand but now that it's doing it on the new PSU I am thinking motherboard. I ran the power calculator on ANTEC's website, input all my info and calculated for PEAK POWER, and the calculator estimated 850 watts peak. The power supply is 850 watts continuous, and i am assuming that there is probably at least a little more than 850 available on this PSU for peak usage. Is there something I may be missing? Any Ideas would be greatly appreciated as I will entertain almost anything before I have to yank my motherboard and send it back. I have also tried Re-reinstalling the HD6970 (complete removal, back to the HD5770's, and back to the HD6970) and no problem with the power. No idea... I am lost!
Sorry for the long post guys, and thank you in advance for your help.
UPDATE! I was re-installing the side panels on my computer case while it was running in windows 7, when I brushed up against the outside of the case....no where near inside, I felt a small static shock and the computer went into a re-boot loop. Not sure if that helps any, but you wouldn't think small static discharges to the case would cause resets....I had to power cycle the PSU to get it to recover...reset or power buttons would only stop the re-boot loop until I let the button go.
As of this morning, I am having the same kind of problem. I haven't done any testing, but when I tried to turn my PC on (from hibernate) it didn't turn on at all. I turned off the PSU for about half a minute, then tried. The lights came on for less than a second, then it just shut itself off. Very weird. I hope someone knows the answer.
EDIT: Left it unplugged for a while, cycled the surge protector, and it now works fine.