How much of the bandwidth does a typical gaming card use on a pcie x16 slot? the slot is 2.5gbs up and 2.5 down right? The reason I ask is because on workstation board the dual pci16 slots are in x16 and x8. would a bottle neck occur in the second slot? at the moment i have the 7950gt gpu. i plan on moving to the quadro soon but even for the geforce card. when does the bottle neck happen. ive even seen on some of the 4 way boards x16 x8 x4 x4. would there be one there? thanks for your time guys.
There are more factor than just the speed of the PCIe slot. The memory on the card can play a role too. If, for example, a card constantly has to load textures from the RAM to the Video memory the PCIe speed become quite important. If you have a 2GB card that can suck in all the textures there are, i'm quite sure it would run like a dream even on a slower PCIe slot.
Another factor is how the manufacturers implemented the use of the bandwidth. If i look at the new 790fx boards (AMDs high end offering) i conclude that AMD is quite sure that 8x speed is enough even for its fastest cards.
There was an article about it on the mainpage once. You should look for it and see yourself.