After increasing the cpu fan frequency from 10000khz
to 30000 my PC worked fine for a day then it won't boot I hear the sound of fans but it shut downs after few seconds like it wants to work but it cant
I tried reseating but it won't

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What kind of PC fan runs between 10,000 and 30,000 RPM? I've never seen one and I've been dinking around with computers for 34 years.

Tunisie - Pc gamer Titan (http://www.sbsinformatique.com/prod-3189-Pc-gamer-Titan.html)
That's my computer I don't know if it is cpu fan frequency but I increased someghing from 10000khz to 30000khz

I would start by setting your bios back to default settings. And see if it boots then. That's a good first step anytime you adjust something too far and encounter a problem. If it doesn't boot then... you have a hardware issue unrelated to recent configuration changes.

I have a powerful computer with 8gb ram and a gtx 660ti power edition but after reseating the bios it became really slow

Go back into the BIOS and load the defaults and then reboot.

After reseating my bios my PC became really slow

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