AIO/PSU Problems

[cyberr_c28z]

Well I got some weird things happening to me.
1. When I start the PC, the PSU clicks and shutdowns then same thing happens again and after 2 shutdowns and clicks the PC boots normally.
2. I've been getting random shutdowns during gaming. Both the PC and the monitor are connected to an UPS. The shutdowns occur during gaming and both the PC/Monitor are shut off. I don't understand why..
3. The AIO temps are strange. When the CPU is not overclocked and using XMP, when stress testing them temps might be higher than 90, now when manually overclocked the CPU to 4.8 and 1.3V the temps are in the 80's, WHY and HOW?
Can someone help me and explain me why this happens, this isn't my first build...

Specs
i7 8700k

ASUS ROG XI HERO
G-Skill 3200MHz 16gb
H115i Platinum AIO
1070ti Zotac AMP!
Cougar panzer evo case
3 fans intake in the from
2 AIO fans intake at the top
1 fan exhaust back