Pls help

Hi guys

I upgraded my pc from a 350 watt power supply and 9800gt 512mb 17 monitor 1280X1024

to

550 watt silverstone power supply and the new gts 450 1gb and a new full hd lcd 1920X1080

my specs are

Intel Q8200 stock
xfx 750i sli
2gb of ram corsair 800 bus 5-5-5-18
evga gts 450

.............................

1. i have problem with game splitsecond my fps are like 10 on the hd resoultion and very high.......and i am darn sure on the 9800gt i was running very high 1280X1024 with 30 fps...i tried to reduce the resolution to 1280X1024 but only 13fps on gts 450..... wast the problem the gts 450 is deffenatly better than 9800gt (HAVEING ALMOST THE SAME PROBLEM WITH F1 2010 ) my pc far exceeds the recommanded specs        

2. i overclocked my card from
824 core to 920
1648 shader to 1940
and memmory from 1804 to 1952

and i did this to reach the evga ftw gts 450 card

but i dont see a single fps increse not even 1 not 1           in any game

i dont know whats the problem pls help
i contacted ebga and the bas***** said we dont garrenty overclock        

3. and is there something bottlenecking my pc is there....and what should i upgrade next