predator g5900 graphics card upgrade

MCFCdaniel

Hello good people, I purchased my Acer Predator G5900 over a year ago. I am an avid gamer and have recently decided to make a few upgrades so that I can max out games like Skyrim etc. Problem is that I could do with some solid advice on what to shop for. My current system looks like this

 

Acer Predator G5900

Intel Core i7 875k 2.93 GHz

ATI Radeon HD 5850

8GB DDR3

H57H motherboard.

 

The psu is a 450 watt and I have been advised that before buying a meaty graphics card that I need to upgrade that, would a 750 watt suffice? Also my biggest question is given my motherboard and other components, what graphics card is supported and would give me the optimal performance I so desperately crave?

bazzah999

i,ve got predator g5900 with i5 prosseser but got 16 gig ram standard graphics gt440 played battlefield 3 not to bad but played .but up graded to msi gt6440 game still played 90 pound but told gtx 560 ti would be better but still waiting for that one  .best of luck