I got it on ebay and its been working fine for a month. 925 is the clock speed on the reference card. My particular model is a sapphire dual x 7970 oc with boost so its slightly higher. The card has a second bios that you can switch to that comes factory clocked at 975mhz and goes to 1ghz with boost. I already tried both bios' and the problem continues. The odd thing is I just ran Furmark and compared the score I got to other 7970's. Amazingly my score is right where it should be. My problem seems to only affect the games I play. I haven't changed any graphics settings in the catalyst control panel so I know that couldn't be causing lag.
I asusme you're using 14.4 catalyst and drivers. Many others have said the new drivers actually made their card perform worse and gone back to 13.12 Also, some games may require the components of dx9 be installed. I think the game you mentioned earlier said dx9. This may also help out..http://www.microsoft.com/en-us/download/details.aspx?id=8109 I am running out of idea's. It could be that the card is having issues and buying off Ebay you never know what you get. I had a secondary card one time in another system I owned back in the 5700 series era and it had a problem running at default memory clock of 1150. It was a 700/1150. I had to downclock the memory to 1100 to make it stabled. Otherwise you get the dreaded vertical line crash.
It's possible you may have a half blown card that just will not run at it's clocks stable. Furthermore, it may not be the card at all and it could be a motherboard/PSU issues. Some builds are just wacky and never run right no matter what you do. I was dealing with this one Asrock system OMG that thing was a lemon. Nothing would work right ram issues, video card issue's. I had to get a new MOBO and start over.
Edited by technonymous, 07 July 2014 - 06:33 PM.