Is my prayer valid or void if I performed ablution with the intention of wiping over my socks, but then forgot to wipe over them and prayed?

Your prayer is invalid and must be repeated because you performed it with incomplete ablution. If you remember this shortly after, it suffices to wipe over your socks and repeat the prayer. However, if you remember after a long time has passed, then you must perform ablution anew, due to the loss of al-muwalat (successive performance of ablution acts), which is an obligatory part of ablution. The long duration considered here is the time it takes for the limbs of an average person to dry in an average time and place.