So - I am pretty sure that PCIe 3.0 os compatible with PCIe 2.0, but will there be any limitations of the graphics card?
Also, is having a good graphics card with really not so good mobo a good idea for gaming? I have done my research and not really gotten a good answer, but it seems that mobo does not really make a difference when it comes to gaming.
OK, first of all PCI3.0 cards are backwards compatible. So plug it in the 2.0 and it runs no problem.
The limitation of 2.0 w.r.t. 3.0 is the maximum transfer rate. 3.0 transfers twice as much data as 2.0 does. However, your card's processing can't handle that.
At 2.0 x 16 you should still be able to transfer more data than your card can process and your performance shouldn't suffer.
Pcie 2.0 will not limit/bottleneck your video card however your processor might. I don't see how your motherboard will affect the video card performance. More importantly, look at your power supply. It may be the #1 reason why your new video card might not work.