Cannot Detect Graphic Card

[Teezet]

Hi,

I have a secondhand ATI HD 5770 Graphic Card, i have used it for some time, but the fan is working slow (30% on AMD Catalyst Control center), i tried to clean the fan and unscrew the fan and the heatsink to clean it, after i put it all together, the fan seems better but my PC can not detect it now? How can i damage it?

When i connect Monitor using the card's slot the monitor does not detect any signal and i connect to the motherboard's it detect signal and start the windows. When i check hrough device manager (while connecting the card on the slot, but using motherboard's port), i did not detect any card on the slot?

Did i damage it? Any help would be appreciated.

Windows : 7 (32 bit)
RAM : 2Gb
Graphic Card : ATI Gigabyte HD 5770 1Gb DDR5
Motherboard : Asus G41M-Combo
Power (SMPS) : Atrix 500T (650w)

 

[Mellon Head]

Did you reconnect the graphic card's power supply connection(s) when you reinstalled the card? The manual for that GPU shows that it needs a power connector.