The PSU looks to be something from 4 or more years ago.
If you are recycling parts, you may find out why they were free or cheap.
I've built my friend a new pc our budget was limited and my knowledge of new components is limited as well so I installed what I taught was a good budget build like 2-3 years ago. AMD FX-6300, HD-7870, 8GB DDR3 1600 MHz Kingston ram, Asus M5A78L-M LX-3 motherboard, Chieftec smart 600w psu, his old hdd and case. I've installed the ram in his older build because it arrived first and he wanted to test is, than a few weeks later everything else arrived I've put together the build but I know we need a custom cooling for the FX-6300 because it runs hot. Yesterday it arrived but we can only meet on the weekend so I can't install it yet. He used it fow a week with the stock CPU cooling but couldn't wait and tried out Rainbow 6 Siege and not suprisingly it overheated the pc and it restarted. Next day he tried out Northguard played for a while and it restarted again, but he claimed that the pc wasn't running hot this time. After that it keeps restarting while the windows is loading for a few seconds. The mouse also start flashing while booting like it get power than cuts it for 3-4 times. He could boot into safe mode to check the event log (I don't know what it is called in english) but it was just hdd and network errors. Now we tried reinstalling the windows 10 but is crashed and restarted at around the point that he needs to enter the name. After that he swithed his hdds and installed it on another one, it went through this time but after a few minuter the screen went blank and it restarted again and it keeps restarting at the windows loading screen after a few spins. Maybe I should mention that when i installed the new motherboard I plugged the front panel pins correctly but when I pressed the power button it restarted the pc, but the case didn't had a restart button so I didn't put much taught into it, so i'm really scared that we got some defective parts.
I really hope somebody can help me with my problem because my friend and I spent a lot of our savings on it and he is getting very dissapointed and I don't want to let him down.
Thank you for any help in advance and sorry if my english is terrible but I hope it was understandable at least.