I'm having a bit of a bad day today, my PC was working fine when I left the room, when I came back it was dead. Infuriating because there could have been some kind of clue in the death, a blue screen, a noise, anything, but I was away for 5 mins and that's when it happened.
I've done a breadboard test with just the 24-pin mobo and 12V CPU connectors in, and I'm getting no beep codes, display, or POST. The PSU and CPU fans spin for a minute and then it powers of. I'm running an ASUS P8Z77-V LK with an EVGA Supernova NX750B PSU. The chip is an Intel i5-2500k (not OCd).
With the breadboard test the CPU and PSU fans spin but there is no power to any of the USB ports. I can have a SSD plugged into the PSU, but when I swap it for a HDD the power shuts down about a second or two after it starts. When I try to plug my GTX 970 into the PSU, everything dies after less than half a second. The green LED for mobo power comes on, and there are a couple of red LEDs that light up when I flick the switches (GPU booster, EPU). When I plug my PWM fan hub into the CPU_Fan all the chassis fans spin too. It also stays on with a DVD drive connected to the PSU and mobo, I was able to open and close it.
For years I had an old 2004 Dell desktop lying around and I could have used the proprietary PSU just to test it. Guess when I finally took it to the tip? Yesterday. Infuriating.
The EVGA PSU is the only new thing I bought new for my build (except for a Phanteks case) but its 3 year warranty expired 3 months ago. (Inf- you get it.)
Asus provides info for beep codes, but regarding no beep code at all it just says to contact ASUS for further inquiry. (Which suggests it could be any of the parts in the title).
It could be any one of the parts, I just don't know, do these symptoms point to one or the other? The way I could go about it is just to buy cheap replacements for each part in turn, to find out which one is at fault. You can get cheap 750w PSUs for less than £30, although I wouldn't want to run my PC with one on a long term basis. You can find either the motherboard or CPU, used, for about £30.
Please let me know which part is most likely to be dead, and I'll start with that one. Can't believe I threw away that old massive proprietary PSU yesterday.