The 1GB DDR5 option is far and away the best. It is the only option that you should consider if you want to play any modern games. If you are just building a basic use system or HTPC, the 1GB DDR3 is plenty.
I have a ( pretty new, so no improvements, i'm afraid ) Cooler Master also but i did bought this before i knew what i know now ( before i was on Tom's ) The internet shop i was buying from advised me this one, meh.
Just some quotes ;
"however it has a major flaw that prevents us from recommending it: noise level at +3.3 V and +5VSB outputs were above the maximum allowed when we pulled 600 W and above from this unit. High noise levels overload and can even damage components on your computer.
The unit lasted until test five, and then two minutes and twenty five seconds later shut itself down. I was able to get it restarted once it cooled off, indicating that the overtemp protection was in play, but then it shut down again when I tried for test five again, thereby failing the hot tests due to the inability to make it all the way to the end. The highest ambient temperature seen was forty two degrees before shutdown with exhaust temps reaching the low sixties. It is abundantly clear to me that this unit's 750 watt rating is not intended to be reached anywhere near the forty degree mark, and to be honest I'm not sure I'd care to run it to 750 watts very often at room temperature either, if I'm going by the numbers from the cold tests.
the Coolermaster GX-750 underwhelmed in just about every way possible. Regulation was only so-so, efficiency was remarkably lower than the 80 Plus test report would have us believe, and the 3.3V rail had more ripple than the last time I did a cannonball into a pool when I was still a three hundred plus pounder. To boot, the unit wouldn't even come close to full power at forty degrees before the overtemp protection came in and shut down the party"
This is not perfect card for hackintosh, neither of those three, 3rd option is the best for all other systems for sure. If u plan to install hackintosh you need to add some extra flags in boot plist file to make it work. Check this ati hd 6670 tutorial for hackintosh if you dont mind and plan to buy it anyway...