Recent issues?
Make sure you have latest non-beta bios and you should be good.
Warranty void: read the terms, I don't remember but if you have any trouble on problems before you send it to repair, remove motherboard battery to remove any data from the motherboard.
But I guess you shouldn't face any issues.
Easiest way to undervolt is to use the BIOS setting Curve Optimizer. Per Core setting, set around -20 and -30. Your system will be unstable if you make it too low. CS2 for example instantly gives WHEA error reports about stability, but you should use Prime95 to see L3 cache errors popping up.