Question Total freeze leading to total failure to boot

[LewisDTC]

Almost an eight year old system with no major faults in the past (blew a psu a few years back) that has until recently been absolutely fine.

Cue a few days back when the whole thing froze completely. I was tired at the time and didn't bother turning the thing back on.

Now a few days later, I'm getting no luck booting at all. Hit the power button and the psu fan spins up for perhaps half a second before the whole thing dies. It keeps boot looping like this until I cut the power.

After breadboarding the thing and removing components one by one, it seems that the problem arises when I plug in the 8 pin cpu power connector. If I remove this, the motherboard stays on at least. This seems to be the same regardless of if my cpu is installed or not. There is no visible damage to the motherboard.

Tried a replacement wire and no dice. I only bought this psu about 4 months back to replace the cheap one I was using after my last broke down: I get the same result with my cheap psu as with my new one.

I thought it might be a processor problem at first, but now I'm suspecting the mobo. I don't have a spare of either to test them further, but wondered if anyone had any thoughts before I go spending money or replacement parts I might not need.

I7 4950k (I think)
Asus Maximus VII Ranger
GTX970 (msi)
8GB Corsair Vengeance RAM
750w EVGA gold+ psu

 

[ChevetteSCx]

We'll start with the 750w EVGA gold+ psu...
1.) What Model?

Now, remove the 24-pin ATX, 8-pin CPU and all other connections to the system.
2.) Do you have a PSU Tester or;
3.) Do you know how to ''jump start'' a PSU and use a DMM/Voltmeter?

Check voltage outputs on all pins of the PSU.
4.) Are they within range? (11.4-to-12.6V and 4.75-to-5.25V and 3.135-3.465V)

Now, the BIG ONE...
5.) Before the system boot loop, do you know or have you ever checked system component temperatures? (CPU/VRM/RAM/HDD/etc.)

6.) Have you tried cleaning/dusting the CPU Heatsink/Fan and Motherboard Heatsinks?
7.) Have you replaced the Thermal Compound on the CPU Heatsink/Fan?
8.) Have you replaced the Thermal Compound on any other Heatsinks on the Motherboard?

Let me know!