Just found this thread -- hope you gurus are still able to see (and reply to) this.
I am in the same situation -- having a dc7700sff and wanting to upgrade the video. Mine is fitted with a 1.86GHz C2D, 4 1GB RAM sticks, 1 1TB WD Green, 1 DVD drive, and a pci wifi card. The power supply is 240W (probably not 80+ -- not sure about this).
My main objective at this moment is to be able to play Civilization V. I actually got an old HD5450 card with 512MB DDR2 :-( and it was able to run Civ V with minimal settings (1366x768 with all effect off), but I'd like to get a bit better effects, and I've read that people with low graphics ran into problem later i the game (with larger maps etc.). So I'd like to get a better card. The choices:
* 5450 with 1GB DDR3: I suppose it will be better, but probably not much, and not a worthy "upgrade". True?
* 6450 with 1GB DDR3: This would be visibly better I suppose, but still not by much -- I read the benchmark results and it does not seem to add a lot to Civ V experience.
* 6570 with 1GB DDR3, 128bit: I am mostly interested in this one. I am mostly interested in this one.
My main concern is power -- the TDP is more than 30W higher than the 5450; will it push the 240W PS? (I could remove the DVD, but I suppose it won't help much.)
More of a concern is that per the tech spec of dc7700, the pci-e slot has a rated max power of 25W. Even the 6450 is over that. Some people say that the pci-e standard is 75W so this should not be a concern, but ...
I will appreciate advice on the choices here (especially regarding the 6570 -- if someone has successfully tried it, please share your experience).
Sean