i don't belive that PS2 works with ATI 5750 and 7750 @1080p with playable framerates 😉
you should check what i wrote to you a few days ago in another thread (internal resolution within pcsx2-config)
what is your aim? which systems do you want to play? everything up to ps2 (including Gamecube and 3DS) or only older systems up to Nintendo DS/N64 PSX and Dreamcast?
and what cpu do you have?