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With everything connected the fans and the standby LED power up, harddrive spins up. I have tried different video cards, tried different memory DIMMS, reset the bios different times, tried different power supplies. Nothing seems to work.
So, the power button can turn on the computer, but won't turn it off? What about your display problem? As odd as that sounds, it's likely you have a short either in the power button, or the front panel.
With your system still breadboarded, disconnect all front panel connections from the motherboard. Using a flathead screwdriver (or similar metal object), jump the PWR_SW pins on the mobo.
The absence of beeps is concerning. Do you have a mobo speaker installed? In my experience, no dispaly is (from most common to least common) usually caused by:
1. Short circuit - Breadboarding can sometimes help; and sometimes not. When you did your breadboard, did you put everything together and test for display, or did you install only the basics (one DIMM, CPU, HSF, PSU, GPU/VGA if equipped)
2. RAM - Failing or dead RAM cause instability and display problems. You didn't hear any beeps; not even the single beep indicative of a successful POST, that could be a problem.
3. PSU - A failing PSU or a PSU that doesn't supply enough power can also be a culprit. However likely it may seem that at least one PSU would work, the only genuine test that has conclusive results would be to test a PSU while connected to the mobo and the system is turned on. In this manner, you could do a voltage test (with a voltmeter) to see if enough power is getting to the mobo.
4. CPU - You say that you've applied a fresh spread of Artic Silver 5. When you pulled off the heatsink, was the CPU attached to the heatsink? Did you check to ensure that when reinstalling, no AS5 got onto a pin? Checked for bent pins (even the slightest bend could cause problems)?
5. Mobo - The least likely is the mobo itself. Damage to mobos is more common than you might think. I've worked on computers that have had DIMM slots go bad, even when using the computer for just the simplest tasks, such as web browsing.
At this point, the likelihood of a bad mobo is apparent. For good measure, I would consider using a digital voltmeter and test any of your PSUs on the mobo.