What power supply do you have that only has SATA connectors? I have never seen one that did not have molex connectors.
You could use adapters like this, but generally if you dont have a PCI-E connector and the card requires one, you likely dont have enough power for it.http://www.newegg.com/Product/Product.aspx?Item=N82E16812816038
I have the Compaq DX7500 SFF, being small form factor it likes to not fit things.
It comes stock with the "Lite On PS-5251-4". It's 250W. I tried to google it but it just wants to show me the PS-5251-7.
More over it has a very limited amount of SATA connectors >.> one for the HDD, one for the DVD. It even has an extra bay for a second HDD- I don't know what's up with that if I can't give it power.
Damn this un-upgradable HP PCs.