Hi, Mike here. Currently I have an HD 6570. But now that I have a job, I'm trying to upgrade to either an HD 6670 or an HD 7750. My first question is, will these both work on a stock Dell 300w psu? That's my first question. Secondly, I know when you buy these graphics card there are different versions like Gigabyte, XFX, HIS and so on. Currently, I have an HIS HD 6570 with passive cooling and it tends to get very hot(Reaching up to around 80C-100C on intense games). Which version of these cards should I get if I want around 60C at max load?