Games randomly stuttering

so ive been having a problem that suddenly started after overclocking my gpu, i did the overclock proply by following a guide, it didnt artifact or anything, but i now get random stutters, like it will be normal fps smooth then suddenly halt for half a second then carry on, ran prime95 for 6 hours and it was fine no errors temps never higher than 81c, tested ram with memtest, allowed 3 passes, ran furmark, max burn, temps got to 80c and stayed there, this at stock clocks. seems fine but obviously somethings wrong

system

cpu: i5 2400 sandybridge stock clocks

gpu:hd 5770

psu: corsair x600 600 watt

mobo8z68-v

ram:4gb gskill ripjaw, and another set only difference between them is voltage, 1 set is 1.6 or 1.65, other is 1.5

all bios settins are default. ive tried just about everytin from reinstalling on diff hard drive, switching ram slots, taking 4 gb out, closed all services, differnt sata ports, differnt sata cables, made sure cpu installed correctly. im lost and seriously am wondering if ill ever fix this, should i take it to a pc repair shop, is it likely they will fix it, its very random and games seem to run fine but every now and then stutter wether high or low settings

Which games? Try lowering your AA settings, and see if that helps. Some games like Skyrim stutter if you set the AA too high, try running the card at stock settings (or just turn down the settings a bit) as not all cards will OC the same. The 5770 is still a good card, but it is getting a bit dated, if you can, grab a 6850 for a gaming boost.

http://www.newegg.com/Product/Prod [...] 6814102908
$145 SAPPHIRE 100315L Radeon HD 6850 1GB 256-bit GDDR5 PCI Express 2.1 x16