from what Ive been reading (I only run windows atm as I have the extra licenses) it makes no difference. win7, vista, xp, *nix are all pretty much the same m/hash wise on the same hardware. what is different is ease of use as win has tons of overclocking and over/under volting tools. *nix, not so much.

the big variables for m/hash production are the core/mem clocks, miner (and its flags), SDK version and CAT version used. each OS/card combo seems to like a different combination to find its sweet spot.

making sure the PSU is drawing fresh (ie not heated from the cards) air may help the PSU efficiency. Im unsure but I do know the hotter they get the less power they can deliver. whether cooler = slightly better efficiency is true or not I dunno but even 1 or 2 % = 3-6 watts on your setup. 

and man, 300 watts that whole system on those two cards? sweet! I pull 300 watts from the wall on a P4 prescott/single 5830 rig. no DVD, other cards, one HD.  Ill have to try undervolting the 5830. cant mess with CPU/mem stuff as that rig is a HP/Compaq business computer work gave me when they retired it. no BIOS options for the good stuff. that thing sat for ages in the basement, never thought Id would actually use it lol.

as a long time folder, starting with a coppermine p3 1.0 years back and now folding with 2 GTX 285s and a Q9650 @ 3.8, Ive always liked the hardware aspect.

so, what hardware did you folks start with back in the day?

as for me a couple month ago i saw bitcoins threads at various hardware sits and pretty much blew it off. like, riiiight.. money from video cards.. as time passed and more threads kept coming up, I started to seriously look into it. at that point I switched my HD4850 (which sucked a folding anyway, but hey science is science) and signed up at the various sites to get the money into a bank account to see if it actually worked. well of course it does.

so.. hardware..

started with the 4850 but soon upgraded to a 6870 in the day to day rig. then replace the HD3850 in the HTPC (it sucked at HTPC duties, no real 23.97 FPS support) with a 6770. HDMI 1.4a!  3D support! 23.97 support! yea!. those pull double duty in the respective rigs  where I can easily justified as legit hardware upgrades. but then..  then a 5830 in an old P4 prescott carcass as a dedicated rig in the basement.

guess the bug has bit. 800-850 M/Hash total. fun,  I know its not gonna make me rich but its more hardware to play with and I can fold with it later if I want.

anyone else want to tell their hardware story?

my sapphire 5830 pulls 300 m/h at 960/354 stock volts (guiminer on xp32 2.1 SDK / 11.6 driver.  -f 15 -v -w 256 flags. havent tried higher clocks as its on a Delta 340 watt PSU, waiting for my Antec 550 trio RMA to come back. then Ill put the screws down.

there are many "sweet spots" - different work sizes and mem clocks can make a decent difference (10-15% maybe).

you can up the f number while gaming but when youre not set to -f 1 or -f 15 or something. your hash rate will thank you.

for my HTPC for instance i run it at f 1 at night (dont care about screen lag), f 30 during the day (so my wife can watch stuff) and its off completely when watching a blu ray rip as I want perfect output.

higher f number = less hash rate. if 24/7 mining it adds up.

thats a kingwin psu. I wouldnt trust its specs. if it were corsair, psp&c, seasonic, antec I would say its good as they are real world rated (actually underrated in most cases).

CUDA is nvidias language for talking to its cards when you want the card to crunch data (as opposed to displaying a scene in a video game). basically its a set of rules on how to get data to the card, what to do with it, and how to get it out.

its a "install and forget" deal.