Hardware acceleration is not used for simple playback. Only if effects or scaling or such are added will it come into play.
With Uncompressed material, a RAID is often required.
The OS drive will have little effect on performance, assuming you have a proper config and are using it ONLY for the OS and programs.
I have a GTX 480 (with MPE hack) and a i7 980x, 24GB ram and a 3-disk Raid 0. I've never been able to get a TIFF sequence to playback in real time. The best I get is probably a choppy 4 frames per second. I know this doesn't answer your question entirely, but maybe it can help a tad.
I myself I'm trying to get find a way to playback TIFF sequences. I'm going to be setting up a 4-disk Raid 0 on an eSata raid box, but I'm thinking at some point it's just getting bottled necked at my port connection. Not sure. Others can probably shed more light on the Raids.
The best way I've been able to adapt so far is to create annoying proxy sequences (hence my repeat posts about Premiere needing proxy capabilities). I drop my TIFF sequence in a new sequence. Render it out in low rez. Drop that new low rez version onto the same sequence so now it has two--one HD 1080 and SD 720 (ok, so it's not really SD). I turn on the SD version and the other one off. I make my cuts and edits on my sequences and then when everythings all nice and purdy, I flip the switch back on the HD version and I'm ready for final rendering.
I have my "SD" version set at 720 so it's obviously smaller than the other clips so I don't inadvertantly leave it on for the final render.
Not a great workflow and adds some steps, but that's been my best workflow so far.