Multi-Gpu went invisible GTX 295- Software issue

(Sys specs below as P.S.)
I have strange issue with my multi-gpu since about a year. Nvidia Control panel usually had Multi-Gpu settings, but that option dissapeared. Normally the gpu itself has two led lights on it, one indicating two sort of lights- green (have power), red (lack of power), and the other led light (right below the first one) which has blue light only and indicates that the second gpu core is working, but the light is off in my case. The device manager shows only one core. I’ve changed my PSU (from Chieftec 650W to Coolermaster 700W) . Tried with another hard drive. I’ve even tried Vista with no luck. I’ve tried different drivers for the card, one, however (196), detects the two cores in device manager, but has yellow “!” on each, saying that windows doesnt have enough resources for two hardwares in one slot. Ive updated the BIOS, also with no luck. The reason why this is happening is that ive disabled the second core from the nvidia control panel, since the game i was trying the gpu on havent been optimized for SLi, and i cant turn the second core back on, because there is none at all according to my windows. Any ideas how to pull the second core back online?

(sys specs- Windows 7 Ultimate x64, i7 920@2.7Ghz, gpu- GTX 295 , Motherb.- X58, PSU- Coolermaster SP 700W, nvidia drive- 296)