I have an HP DC7800 mini tower, duo core 3.0ghz, 8GIG Ram,1 TB HD...I bought the GeForce 740 and I 500 watt PSU, PSU didn't fit in case nor did any connectors fit into motherboard (extremely dissapointed).I need a graphics card that can run off a 320watt PSU and can also run off the motherboard, since there are no more connecter on the PSU for me to use...I heard the GeForce 750ti was made for that? but some models need to be connected the PSU...which maker and model do I get, should I get the GT 640? I'm really just trying to run war thunder on medium setting...thank u so much