Question Tried overclocking CPU in BIOS → set BIOS to default → huge fps drop

[Boalski]

Hi, I hope you can help me with this issue, good luck!

Specs:

Intel Xeon x2670

Sapphire HD3560 (upgrading later)

ASUS Sabertooth x58


I bought this pc a few days ago (used), I tried to overclock the CPU in the BIOS. It overheated and didn't shut down, so I shut it down (all cores around 90C). The performance was, I think, because of the overheating worse.
Then I thought, I'll just go to the BIOS and set the settings to default! But the performance wasn't better compared to the overclock (temps are NOW around 50C-60C at gaming). I tried it on Minecraft, before I was getting 60-80 FPS, after 15-25 FPS. Team Fortress 2 is getting on 1080p on low setting around 50fps (Team Fortress 2 is a less heavy game, at least on my old crappy laptop).
Also the CPU clock and GPU clock are normal, at least, when I'm gaming. When I'm not gaming, the CPU and GPU are around half the clock speed, but I heard this is normal.

By the way, I'm not so advanced in the BIOS-settings (because that's where I think it did go wrong).

So, my question is, what did I do wrong? And how do I solve this promblem?

 

[Phaaze88]

I hope you at least had a good cooler on the cpu before you attempted this... what is the cooler?

If bios defaults didn't work, then clear CMOS?

Other than that, the damage is likely already done.

 

[Boalski]

I hope you at least had a good cooler on the cpu before you attempted this... what is the cooler?

If bios defaults didn't work, then clear CMOS?

Other than that, the damage is likely already done.

I have a cooler master hyper tx3i. But if the CPU is damaged, wouldn't it just be dead? I mean, I thought that if a CPU is damaged, it just would not work. But if it's possible to partly damage the CPU so it will lose performance, then I think don't think that's what happened.
I resetted the CMOS (got the CMOS battery out for 30-60 sec), didn't fix anything, but I had my PC plugged into a cheap power circuit. And I got it out of it and it somehow managed to fix it! (I don't know if it's because of that or just plugging it out and in, but it's fixed👍)