Hello people of Tek Syndicate forums. I need to know if getting a 2nd 7970 will give me atleast a 50% preformance increase in my current rig. I have been considering getting a 2nd one for a while now. Newegg recently put a promocode on a sapphire 7970 bringing the price down to around $320 with shipping. I do video editing and gaming on my computer along with recording so having a 2nd graphics card might be usefull to me but by how much is what i would like to know.
I doubt that you would see any sort of in-game performance increase at 1080p. That is unless you think that the performance from one is sub par. As far as editting goes, I have no experience, and no idea. Now, the price is pretty good, so if you were to do it, I guess that now would be the time. The purchase would be more justified at a higher resolution, but since I don't know what resolution you game at, I am assumig the most common one (1080p). Have a look at some benchmarks and compare the single to multi gpu 7970 configurations. You make the call.
If you are taking advantage of OpenCL for your video editing and encoding, you should definitely get another HD 7970. That being said I strongly suggest you replace that motherboard before you do. With at least a 990FX motherboard that has at least 6+2 power phase and 2x PCI-e 2.0 x16 slots that run at least x8/x8 when in crossfire.
Performance hit from having 2.0 x8/x8 is negligable in terms of gameplay but he will see a small performance drop in OpenCL computing as opposed to using straight 2.0 x16/x16. Regardless, having 2 HD 7970s for OpenCL computing is a massive difference from only having one.