Question My PC becomes laggy when playing games ?

[Max Arthur]

my PC is a low end but still can play games like Far Cry 5 with low graphics, roblox with high graphics, or CS:GO with medium graphics.
the spec is:

Intel Core i5-650 3.20GHz
8GB of 2133GHz RAM
Nvidia GeForce GT-1030
450W PSU
Windows 10 Pro

Somedays when i play games on my pc, my house has a power failure. Then when the power is turn back again, i turn on my PC then play games again. Then like about 10 minutes later my house have power failure again(heck i hate my country & electricity company). Then when it turn back again, i turn on my PC but its lagging as heck. i try to defrag and it just make it like 5% faster. And when i try to play games it just become even more lagging. I try to update my windows but its just make my PC have a blackscreen. Then i try to reinstall my windows, its turn back to normal its not lagging again. But when i play games, yeah its still lagging like now i get 10 fps on Far Cry 5, i can't play roblox at high graphics, and CS:GO? i play it at low graphics but sometimes it has FPS drop. It is because the PSU or something?

 

[rgd1101]

cpu/gpu temp and usage during the game?
brand and model of this 450w psu?
health check your hdd?

 

[Max Arthur]

cpu/gpu temp and usage during the game?
brand and model of this 450w psu?
health check your hdd?

CPU usage is around 50%-60% with temp around 60-70°C
GPU usage is around 20%-45% with temp around 45-50°C
Corsair CV450
i use 240GB SSD and 1TB HDD, all good
(sorry for the late reply)