hope someone can help me out , i bought a EVGA GeForce GTX 570 HD 2560MB of a m8 who won it in a competition and sold me it for £150 (bargain
), what i want to do is get another card to sli them ,do i have to get the same card or could i buy one of these below to run sli
http://www.overclockers.co.uk/showproduct.php?prodid=GX-140-MS&groupid=701&catid=1914&subcat=1341
http://www.overclockers.co.uk/showproduct.php?prodid=GX-175-OK&groupid=701&catid=1914&subcat=1341
any advice would be appreciated

http://www.overclockers.co.uk/showproduct.php?prodid=GX-140-MS&groupid=701&catid=1914&subcat=1341
http://www.overclockers.co.uk/showproduct.php?prodid=GX-175-OK&groupid=701&catid=1914&subcat=1341
any advice would be appreciated