Do you remember what settings were changed in BIOS?
Did you try reloading default settings or a BIOS recovery?
You may also try moving the BIOS jumper to configuration mode for the maintenance menu to appear. See pages 59-61 of the Technical Product Specification.
1. I changed ram overclock settings
2. can't do that because the computer only stays on for 3 secs and turns on again (It repeats)
3. same ^^^^^
Did you try booting with only one memory stick?