One of my HDDs only had 25MB/s write speed after a clear cmos, so i went to the bios and all my HDDs were set to AHCI. so i put them all to IDE. when i wanted to boot i got a bluescreen, i went back to the BIOS and set all back to AHCI, did the test again and now i suddenly have 90MB/s. i can't explain how that happend.