GTX 260 not recognized

My system has a 350W power supply vs 500W recommended, so I attached the 6-pin supplemental power connectors to a separate 200W power supply. When I boot the system, the card fans are noticeably running but the card isn’t recognized. When I try to install the nVidia drivers I get: “WARNING: You do not appear to have an NVIDIA GPU supported by the 331.67 NVIDIA Linux graphics driver installed in this system” message. Tried modified the BIOS graphics setting from Auto to PCIE, but it doesn’t seem to help.

Am I doomed with my current hardware setup?

Seems like as you mentioned, the card isn’t recognized in the BIOS, thus your current setup won’t work. Either upgrade the power supply, or try the card in another system to make sure it is working.