Question PC Turning Off Randomly

[Dusky Crow]

So this has been a problem for about probably a month or two, but now has just gotten to a critically annoying level. Before my PC would just cycle through on and off while booting up, which was no big deal, but now it's turning off randomly in use. Whether it be idle, simple browsing, or playing a game. There is no real consistency in when it turns off, but it does seem to happen the most during boot or after boot. Thinking it was Windows, i've reinstalled it to avail. And I also bought a gold 550W PSU thinking it was definitely a PSU issue. Which it doesn't seem to be the case either. I've tested, but not thoroughly tested the memory via the Windows Memory Diagnostic Tool, and ran it 3 times (6 passes) in standard diagnostic to see if it could catch something. It did not.
HOWEVER, as I was writing this after linking my RAM specs, the timing is different compared to what it used to be compared to like a week or two ago from when I made a different thread.
The old timing used to be @ 800MHz (9-11-11-29) but is @ 665MHz (9-9-9-24). I don't exactly know enough about PC's to know if this is indicating a problem, or if this is normal, but I think memory isn't supposed to flip flop on timing. Is this indicative of bad RAM or am I going to have to look around for a different cause?



Specs:
Operating System
Windows 10 Pro 64-bit
CPU
Intel Core i5 3570K @ 3.40GHz 30 °C
Ivy Bridge 22nm Technology
RAM
16.0GB Dual-Channel DDR3 @ 665MHz (9-9-9-24)
Motherboard
Gigabyte Technology Co. Ltd. Z77-HD3 (Intel Core i5-3570K CPU @ 3.40GHz) 28 °C
Graphics
X191W (1440x900@75Hz)
2367 (1920x1080@60Hz)
4095MB NVIDIA GeForce GTX 1070 (Gigabyte) 38 °C
Storage
931GB Western Digital WDC WDS100T2B0A-00SM50 ATA Device (SATA (SSD)) 25 °C
931GB Western Digital WDC WD10EZEX-60WN4A0 ATA Device (SATA ) 27 °C
Optical Drives
TSSTcorp CDDVDW SH-224DB ATA Device
Audio
Realtek High Definition Audio

 

[JeffDaemon]

If it is not the cpu then it is the motherboard, because the motherboard controls all on/off actions. Aside from ensuring chipset drivers are properly installed and that the latest bios is installed, it could very well be just a bad motherboard.

 

[Dusky Crow]

I feel like i'd be seeing obvious signs of wear and tear on the CPU through gaming performance drops. So I don't think it is the culprit. And i'm not sure about the motherboard. Would a motherboard just randomly go bad? Since I already bought a PSU, i'd rather not drop more money on a motherboard if I don't have to.

 

[Dusky Crow]

It appears now that the PC is turning off a lot more frequently. I believe I eliminated RAM being the issue and I tested each stick individually in the system. The booting problem persisted. Kind of afraid to turn the thing off now because don't think it's gonna come back if I do. It turning off and on constantly always happens most after boot, and it seems to want to die a lot quicker now. Almost instantly in some cases.