Relaxed Timing : if you have 4-4-4-12, relaxed will be 5-5-5-15 or even more. Normally in your bios youll see AUTO as timing. just manual it.
For the clock, you have ddr2 800mhz you can raise or lower this clock in Bios, this also can be on AUTO mode, just manual it.
Lowering V will result in instability. youll have to Lower clock or add timing. BUT raising the V help stability (at cost of heat and can damage Ram if to high). By raising V you can use more aggressive timing (4-4-4-12 or lower) and/or Higher clock.