Core i7, 4 gigs of ram, radeon hd 4870, 1gigwatt power supply, asus mobo, 1gig 5400 rpm sata hd. HDTV display, has prob on lcd monitor as well. All games have the problem, but LoL fixed this problem with http://leagueoflegends.wikia.com/wiki/V18.104.22.168
patch that fixed the fps issue. However the audo now has massive issues, but it no longer frame skips during this time.