Newly Built Computer Won't Post - Cycles over and over after shutting off randomly

About a week ago I received all of my parts from Newegg and Amazon and built my first computer. It has been performing admirably with no problems at all until today. I was surfing the web when the computer shut off completely. The power led stayed on for about a second after the screen went off. It automatically restarted, but did not post, with all fans at full - not spinning down as they usually do.

Every time I've restarted after this, the fans (case, CPU, and PSU) turn on for a split second, and then stop. Every few seconds, they repeat this cycle. The only light that turns on, and only for a split second, is the CPU light. This all happens with a small sound that I can only describe as a small spark. I have pinpointed this sound to the motherboard.

I have reseated all of the cables, replaced the RAM in every configuration possible, and have breadboxed the rig to try and troubleshoot further. I also reset the motherboard CMOS. The PSU passed the paperclip test, with idle voltages of 12.19, 5.10, and 3.38 on the 24 pin ATX cable, measured using my multimeter. Currently, the only cables I have plugged in are the 24 pin ATX and 8 pin CPU cable, and the computer still will not POST.

The only thing I can think of that could potentially be a cause of this would be a Prime95 test I ran a few days ago. I had a stable 4.6 GHz overclock with a manual voltage of 1.280 volts, and had just finished running IntelBurnTest, which passed. A few people had let me know about Prime95, so I decided to run it on its normal settings. Once I had started it, a loud whine came from either my motherboard or power supply, so I immediately turned it off. This was a few days ago, could that have been the sign of a failing capacitor or voltage regulator chip in my power supply or motherboard?

If you have any ideas, please let me know. I am currently at a loss. I can RMA my motherboard or PSU if necessary. Thank you for taking the time to read this.

This is my part list:

CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor
CPU Cooler: Noctua NH-U14S 55.0 CFM CPU Cooler
Motherboard: Asus Z170I PRO GAMING Mini ITX LGA1151 Motherboard
Memory: Corsair Vengeance LPX 16GB
Storage: Samsung 850 EVO 500GB M.2-2280 Solid State Drive
Case: Fractal Design Node 304 Mini ITX Tower Case
Power Supply: Silverstone 500W 80+ Gold Certified Fully-Modular SFX Power Supply
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  1. I don't know what, but... something obviously messed up. I'd say RMA both just to play it safe. And then put it all back together with new stuff without overclocking initially.
  2. Samaratin said:
    I don't know what, but... something obviously messed up. I'd say RMA both just to play it safe. And then put it all back together with new stuff without overclocking initially.


    Thank you for your response. Unless I get any more information from this thread in the next 24 hours, I'll RMA both and close this thread.
  3. the alternative is, testing each of your parts one by one in a separate working pc
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