Hi, I have never tried posting here before, but I'm not sure what to do about this problem and I was hoping somebody could help shed some light on the subject. This happens occasionally (maybe 1 in 4 times) when the system goes into standby mode when inactive.
The computer appears to stand by and the case fans/LED's all go off, but the LED's on the USB keyboard and mouse stay on. When I try to wake the computer from standby, the keyboard/mouse will not wake it. In fact, the reset and power button also have no effect. The only way I am able to boot the system is to unplug the power or shut off the power supply for 5-10 seconds, then turn it on. From what I have read, the answers seem to be that I should just fully disable the standby/hibernate mode since it is a desktop, but what I want to know is whether there is a hardware problem that I could possibly fix with an RMA. I just built this computer a couple weeks ago, so I still have time on warranties to get a replacement part if something is bad.
I am using Vista 64 bit with a Gigabyte GA-MA790X-UD4P motherboard, XFX Radeon HD 4890 graphics, and 8 GB Crucial DDR2 1066 SDRAM if any of that is relevant to the discussion.
Go to power settings you will notice you have Stand by on, and for the "Harddrive shut down" on.
What happens is your computer goes to stand by mode, then later shuts down the harddrives. Without the harddrives to operate OS, your stuck with a PC with power on with no display, no OS.
A lot of times the reset button wont work here, and neither will the power.
Go to Control Panel> Power options> You might need to go to Advanced. But look for the "turn off harddrives" and make sure it is OFF. After that enjoy
I know this is old, and I hope AsAnAtheist's advice helped you, but I recently had a similar problem with similar hardware. (A Gigabyte GA-MA790XT-UD4P mobo, Gigabyte Radeon HD 4670, and 2x2GB Crucial DDR3-1066 RAM, Windows 7 Home Premium 64-bit)
A few weeks after I built my system, it would go to sleep normally (S3 mode), but it wouldn't wake up at all. The LED's on the case would light up, but none of the LED's on my keyboard or mouse would light up at all, and nothing would come on screen. After hitting the reset button on the case, I'd get an error tone (One long beep followed by two short ones) for a graphics card error. Forcing it to power down and turning it on again got the same result, and the only solution was to literally unplug it for about 10 minutes, plug it back in, and turn it on. I tested it for the next couple of days and found out that it could shut down, start, and restart normally; it would come out of hibernate just fine, but not S3 sleep; S1 sleep mode worked fine. I swapped out the video card, and that seemed to permanently solve the problem. Before I RMA'd the thing, someone from Gigabyte tech support asked if I'd tried doing it with one RAM stick. So, I reinstalled my old video card and tried running S3 sleep with each RAM stick by itself, and it worked fine both times.
And when I put both RAM sticks back inside...it worked fine, and has ever since.
As near as I can figure, I somehow didn't install one of the RAM sticks all the way when I put the thing together, and it took two weeks to become a problem. So if you're still having problems--god forbid--then that (or doing that for anything else you have) might help.