- replaced stock radeon 4750m with 6750m, and I am pretty sure other MCX cards could do the trick Any other mods available on this machine? I'd like to get usb3 on it at some point, maybe a FW dock of ...

TL;DR, I'm looking to replace the HDD in my iMac (this one), and wonder what's recommended between about 2 and 4TB, with a big emphasis on cool and quiet running ahead of reasonable performance.

Speedy all-in-one PC runs Windows 7 and OS X, but lacks extras like multi-touch, Blu-ray, and a TV Tuner. Performance gain over previous 20-inch iMac is marginal, but the new screen is much improved.