660ti GPU utilisation is just 42-58 % while heavy games like BF3 GTX 4

GPU utilisation is just 42-58 % while heavy games like GTX 4 episode from Liberty ,
also in crysis 2 many times it is just 70-80% at 1600*900 resulution
and quality is maxout

in COD MW3 and black opps it fails to maintain 60 FPS constant

in Battlefield 3 Armod kill utilization is just 43-73 % while FPS are below 30-45
and why effective memory is 3000 Mhz instead of 6000 mhz

while few days back my gpu utilization was 90-110 % in bf3 but in 2-3 days it is making me sad
why gpu utilisation sucks in most of games while it was working fine during 1st 5 days when i buy

is my gpu is half-Dead and go for replacement ??
my specifications are i5-650 , 16 gb 1333 MHZ ram , and PCIe 2.0 slot

and 3000 mhz memory is a problem of PCIe 2.0 ??


http://farm9.staticflickr.com/8457/8...441a52f5_b.jpg
http://farm9.staticflickr.com/8306/8...185e42ab_b.jpg

and many times it underclock gpu , utilisation 30 % and fps 20 , hollyshit
help me I think i made big mistake buying gtx 660ti instead of HD7950