Thank you for the list! Do you maybe know where can I find explanations what does each option do? I know only half of them and I already use some of them.
Actually it's not (but it was) a fork of OpenBSD's allocator, but rewrite of a fork. They wanted too much changes so they decided to rewrite it from scratch.
On laptop with Ryzen 5 5500U (12 threads) it takes 50 minutes and on desktop with Ryzen 7 3700X (16 threads) it takes 20 minutes. I use all threads to compile the kernel.
It compiles way waster with Gentoo, because it has minimal config. I used the default config from Arch repos and modified it. It's full of unneeded drivers, but I'm scared of disabling them. I already disabled wrong drivers a few times and had to use different kernel to boot.
XMP is somekind of overclocking, but I disabled it.
Its not only one bit flip but at leats two (in a single byte), I figured out using addresses in the errors.
I was also scared that it's the cpu, because it was the most expensive part when I build the PC. Thankfully I think it's not, now I'm running memtest again with no errors without one ram stick.
I disabled XMP (overclocking, but not really) and still errors. I removed one stick and the test is currently on 35% with no errors (thats new record). I will also try with other one to confirm its defective. Thank you :)
Now I feel stupid...