Computer Randomly Won't Boot

[Dattebayo]

I want to be as thorough as possible, so I'll probably try to post some sort of tl;dr at the bottom because I wanna make sure I leave nothing out.

I bought parts for a PC that I checked compatability of with PC-Part-Picker listed here: http://pcpartpicker.com/b/qNt6Mp

I made this PC about 6 months ago. It was the first one I've ever made, but everything ran well.

I moved to a new place around 2 weeks ago and everything was still working just fine, running perfectly fast and with pretty low temps for summer time as far as I could tell. There was no apparent damage from moving.

I usually leave my PC on all the time. Last night, I was watching some shows (so not doing anything intensive) and then I closed every window, but left the PC on and the monitor off.

When I came in this morning, the PC was off and refused to turn back on.

I looked at many different FAQs and such, and I think it may be my motherboard, PSU, or CPU. What happens is that I can connect the power to my Z77 and it will always stay powered and if I try to turn it on, the fans start to spin and some lights come on, but it won't really start.

When I plug the 8-pin (4+4) CPU cable up to the PSU and motherboard, the CLR_CMOS button will briefly flash its light and then it's all dead until a hard restart (like unplugging the PSU and then plugging it back up).

RAM, GPU, SSD, HDD, etc. aren't making any differences. It's always just plugging up the CPU cables that stops it. The GPU fans will spin if the GPU is plugged up.

From that, I want to assume that the GPU, SSD, HDD, and the PSU (because it powers the motherboard and the GPU) are not a problem.

Where I'm lost is whether it's the actual processor (which appears to look fine to me), the cable for the CPU (but I tried a working spare to no avail), or the motherboard.

Additional info is that the Z77 gives me no sort of debug code or anything. When the CPU cable is connected, it's as if the motherboard is basically dead.

The Z77 has a switch BIOS button, but they both work the same for this issue. No change.



tl;dr: CPU won't boot. Maybe it's the CPU or motherboard? Potentially the PSU? Read the last few paragraphs for more info.

[Salmon Trout]

What does 'tl;dr' mean?

[Salmon Trout]

When I plug the 8-pin (4+4) CPU cable up to the PSU and motherboard, the CLR_CMOS button will briefly flash its light

You did this with the PSU connected to the AC?

and then it's all dead until a hard restart (like unplugging the PSU and then plugging it back up).

See above?

RAM, GPU, SSD, HDD, etc. aren't making any differences. It's always just plugging up the CPU cables that stops it. The GPU fans will spin if the GPU is plugged up.

Where I'm lost is whether it's the actual processor (which appears to look fine to me), the cable for the CPU (but I tried a working spare to no avail), or the motherboard.

Could be the motherboard and/or CPU and/or RAM. Hot-plugging/unplugging motherboards is a recipe for disaster.

[Dattebayo]

What does 'tl;dr' mean?

Too long; didn't read. (Sometimes people don't want to read the non-essential info, even if it could be a clue to what happened. Sorry bout that).

[Dattebayo]

You did this with the PSU connected to the AC?
See above?

Could be the motherboard and/or CPU and/or RAM. Hot-plugging/unplugging motherboards is a recipe for disaster.

No, I didn't; it wasn't hotplugging. I'm just saying there's a difference once the CPU cable has been plugged up.

Like, I'd try it without it and the fans would spin for about 2 seconds.

And then I'd hit the IO switch on the PSU, unplug the PSU's wall outlet cable, and when the mobo lights went off, I'd plug in the CPU cable and then I'd re-plugin the PSU power and then flip the IO switch again.

Trying it with the CPU cable in, the fans don't even spin. The CPU doesn't appear to have bent pins or heat damage. I don't -think- the motherboard has heat damage either, but I can't really tell. It's black.

Even if I had hotswitched, the problem that appeared before I took anything apart is identical to after testing with the CPU plugged in to the PSU or not.

[pcurtj1974]

Sometimes taking everything out and putting it back together fixes the problem. I'd look for a short somewhere, screw floating around or some other metal touching the MB

[Dattebayo]

Got a new motherboard (ASRock Z77 Extreme6) that is showing signs of working, more or less, but it's not posting. It gets stuck at Debug Code 72: South Bridge Initialization no matter what is plugged in or not.

I can find no one else with this same error on Google.

[jason2074]

No posting since a motherboard replacement might point to a bad processor though rare but it happens. There are pins and holes so might wanna check each end just to verify nothing is loose or heatsink also is not properly seated.

[Dattebayo]

I'm RMA'ing the CPU and PSU simultaneously for hopes that it must just be one of those two (after having replaced the motherboard).