Computer suddenly stopped POSTing

My computer worked fine two days ago, but now it no longer POSTs. When I go to start it the power comes on and the fans run, but I do not receive a signal to the monitor. Also, the mouse lights up (but not the optical sensor part) and the keyboard caps/num/scroll lock lights turn on (and I cannot toggle them on/off).

A key clue may be the fact that over the past month or so, the computer had been starting up properly but about 40% of the time the mouse and keyboard were unresponsive upon bootup. Windows 8 would load just fine without any problems and the monitor displayed an image. Rebooting would fix the problem. Could this be evidence of some sort of a degenerative problem on the motherboard, such as a capacitor dying out?

Overall, I don't think the power supply has been overly-stressed since I don't run too much on it. This computer was built by a workplace friend and I pretty much got it brand new back in late January 2013, so I've been running it heavily for about 1 year and 8 months. The case is an Antec 300 which does not include a built-in mobo speaker, so as of now I don't have a mobo speaker (so that I can listen to beeps).

I have some experience with working on hardware and removing/installing components, but I'm by no means an expert and I don't have my own test bench or spare parts lying around, etc. Any suggestions on what I can do to try to diagnose the problem and determine the failed component? Would unplugging the power supply and removing/replacing the motherboard's battery be worthwhile to try to power down the whatever juice lingers in the motherboard? Would it make sense to reset the CMOS/BIOS?

The major components are:

Motherboard = Asus P8Z68-V LX

PSU = 550w modular Antec Basiq

CPU = Intel core i5 3570k overclocked to 4.2 Ghz and water cooled (system has been rock solid with almost zero crashes)

GPU = nVidia GeForce GTX 560

RAM = Generic DDR3 1333, 8 GB, 2x2x2x2

Not that anyone cares judging by the lack of responses, but...I removed three of the four 2 GB RAM sticks and it BOOTS up and goes into Windows! This is a simple problem that I can solve! I'm so happy.

WhipperSnapper said:

Not that anyone cares judging by the lack of responses, but...I removed three of the four 2 GB RAM sticks and it BOOTS up and goes into Windows! This is a simple problem that I can solve! I'm so happy.

Click to expand...

Definitely some other interesting symptoms for a RAM issue, perhaps the slot is bad or just a stick. I'd at least throw in a second stick since it's dual channel and I doubt all 3 are bad. Next step I would do is determine if it's a slot or stick issue by testing a second stick in each slot. Once you confirmed it isn't a slot issue then test each stick to find the bad one.

Sorry, I didn't see the post yesterday, but my son's rig which has a similar board, a z68 asus, has boot/post issues with certain usb devices plugged in. He typically has to remove all usb devices, let the system boot and plug them back in one at a time. Doesn't happen often, but enough that he knows what to do when it does happen.