Question PC crashing and showing black screen ?

[lazy_buffalo]

Hi, I've been facing an issue for a couple of months now. I once took my CPU out to replace the thermal paste due to high temperatures. When I put my CPU back, it was over throttling it's clock speed and whenever I tried to launch a game the whole screen would go black and restarting the system was the only option. I then plugged in my old Radeon HD 7950 in and it wasn't crashing then. I don't know what the issue is, my guess is that my new RX 6600 is too powerful for my i5-3470 and it's causing a bottleneck. But before it worked just fine. I've tried many solutions but unfortunately none have worked for me if you have any solutions please write them down. Any help will be massively appreciated
Thanks.

PC specs:
Asus P8B75-M
Core i5-3470 3.20Ghz
Amd Radeon RX 6600 (Gigabyte Eagle)
2 x 500GB HDD
1 x 180GB SSD
8gb RAM (2 x 4gb)
Corsair VS550 (used)
Windows 10 64 bit

No errors, just crashes anytime a game is open.

 

[Ralston18]

Update your post to include full system hardware specs and OS information.

PSU: make, model, wattage, age, condition (original to build, new, refurbished, used)?

Disk drive(s): make, model, capacity, how full?

What error codes, warnings, or even informational events are shown in Reliability History/Monitor and Event Viewer?