Help me choose a new graphics card

[AmpFeare]

my specs

CPU
AMD Phenom II X6 1055T 2.6 ghz
Thuban 45nm Technology

RAM
4.00 GB Dual-Channel DDR3 @ 713MHz (9-9-9-24)

61 °C
Graphics
Acer S201HL (1280x720@59Hz)
ATI Radeon HD 5770 Series (ATI AIB)

PSU is 750 watts

im just wondering how far i can upgrade my gfx card with my 750 watt psu. thanks everyone

 

[cliffordcooley]

Radeon HD 6990

750W Watt or greater power supply with two 150W 8-pin PCI Express® power connectors recommended.

GeForce GTX 590

Maximum Graphics Card Power: 700W
Minimum System Power Requirement: Two 8-pin

 

[Relic]

You didn't specify what power supply you have so I will assume it's from a reputable vendor in which case enthusiast cards should work. However your current monitor the Acer S201HL has a max resolution of 1600x900 which would make those cards an overkill imo.