checking graphic card speed

Hi, is there anyway of checking the see if the graphics card is running at full speed, because i have an hd4870x2 and i am having serious performance problems with it i.e settlers 30-35 fsp, bioshock 35-40, and crysis on high settings with no aa 30-35fps.

i have installed a program called sandra lite which gives detailed system information and when selecting motherboard details and pci express details is shows my pci express slot speed of only 5.0GB/s, which i think is meant to be over 12GB/s, or am i reading it wrong?

My specs:
asus rampage formula x48 motherboard
gigabyte hd4870x2
q6600 o.c @3.0Ghz
zalman 750w psu
3GB ram
500GB hard drive
2x 320GB personal media drives
raidmax sirius system case

p.s. i have installed all latest drivers for bios, gpu, windows updates and for the motherboard chipsets, and also i have read that you can check to see if the 2 gpu cores are running?