Welcome to the forums, newcomer!
Ever since I upgraded my CPU about a year ago I've been having constant crashing issues.
What processor were you on prior to the upgrade? How are you cooling your processor?
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Besides the CPU, I already swapped out my SSD and my motherboard.
Did you reinstall the OS? If not, that's your problem.
Specs: Asus Tuf b550 Wifi II
BIOS version for your motherboard?
Evga 650w 80 plus Gold
EVGA have a number of 650W 80+ Gold rated units, which one do you have?
Also surely 650W is more than fine for my specs?
A PSU from 2017 will not output the same amount of power after 8 years. Just thought you should be informed of that.
I am leaning more towards the PSU being the problem because it's older but at this point I have no idea, and I definitely don't have the money to simply swap out both components.
Source(borrow, not buy) a reliably built PSU that can deliver 750W of power to the entire system, from a friend or neighbor in order to rule out your PSU being the root cause of the issue.