PSU, Mobo, case (switch) or CPU?

[HHumbert]

Oh vey! Because of a CPU upgrade, I changed out my Gigabyte GA-EP45-UD3R motherboard to a newer Gigabyte Z97C-GAMING 5 Mobo. I kept my Corsair TX-850w PSU because that seems to have more than enough power to do my single CPU, and my single GPU to my calculations.

When I put everything together, slipped in the (new) DDR3 RAM, CPU, cooler, plugged in the power supplies, etc, I'm getting a weird situation...

When I press the power button, it comes on for about 4-5 seconds, all the fans kick on (incl CPU fan) and then it just shuts off again. It then powers back on, and goes through this whole loop ad infinitum.

I used a multimeter to check the live voltage of PS_On on the 20 pin ATX connector, and it seems to drop of its own accord to 0vDC. Then it comes back up to 3.3v.

Weird. Could this be a reset switch problem? Maybe a power switch? I disconnected the reset switch from case to the Mobo, but that doesn't seem to effect the results.

Needless to say, I never get close to the POST.

Any ideas?

 

[meeshu]

Check that all cables that need to be connected are indeed connected (properly); this includes the CPU auxiliary supply.

Make sure DIMM's and video card seated properly.

Try booting again.

If there are still problems, disconnect case power switch connector from motherboard and short the two boot pins on the motherboard using a screwdriver blade or similar metal object. If computer boots/runs then the case switch may be faulty.

If there are still problems, then using one DIMM at a time, and in different slots, try booting again. If computer boots/runs then some DIMM's and/or slots may be faulty.

If there is still booting issues then remove the video card and try using motherboard integrated graphics instead. If computer boots/runs then the video card is faulty.

Still got booting issues? Try another PSU (at hand or borrow one). If computer boots/runs then the original PSU is faulty.

If the computer still doesn't boot (properly) then the motherboard is most likely faulty.

 

[phasseshifter]

clear the cmos refer to your mobo manual on how to do this

also check you front panel header you may not have it wired correctly if in doubt just connect the power switch only..