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The Sapphire 1GB 6950 is $250 shipped on newegg, plus there's currently a $20 MIR but assuming that doesn't work I should still be able to get 420MH/s out of the card with proper overclocking. At the current difficulty level thats ~.75BTC/day and I realize this will drop about once a week but I still feel that it will be profitable, and in any case my desktop could really use an upgrade from an old 4550.

Anyone think this is a bad idea?

You won't get anywhere near 420MH/s out of that card...  More like 325-335...  It's not a reference card so you can't unlock the shaders on it...  Otherwise it's a good card.

I use a pair of 6950s (unlocked to 6970s) and I don't get 420 each. At most (as OC'd as any software allows) I get 360 a piece (Peak of 720 MH/s total). I'd say it's a good investment, but note I didn't buy these for mining, I'm an enthusiast gamer and found mining recently.

Ah, thanks for the input. Still think I'm going to go with it, I'd love to step up the graphics on my games.

i have unlocked cards and oc to 960core they pull 410-415Mhs each

Do you have this exact brand/model?

Mind if I ask what your other settings are?

I have a question, were can you actually find if the card is reference or not? I have two GTX 470, that I got for gaming, and I've only ran across a random forum post saying that they are reference PCBs even though they have non reference coolers and clocks to then.

Reference cards aren't made anymore, and they specifically don't have custom coolers etc. on them. If you see a card with a special cooler or similar modification, it isn't reference. If you want to be absolutely sure if it's reference, look at the card itself and to the left end of the PCI port is a small black two-point horizontal switch. If the switch is there, it's reference. If not, it isn't.

I thought the shaders can be unlocked on non-reference 6950's, and it can be overclocked just OK - as with other cards.

Are you saying this is not the case? 

The only ones that are guaranteed not to unlock are the Sapphire non-ref with the 1 large fan in the center.  The other non-ref are hit and miss.  I have personally unlocked the shaders on this card http://www.newegg.com/Product/Product.aspx?Item=N82E16814150523

Anybody who claims it doesn't work on anything except reference design cards is misinformed.

This is what I thought ^^

I own one of the older 2 GB Sapphires (http://www.newegg.com/Product/Product.aspx?Item=N82E16814102914) and was able to unlock the extra shaders.  I'm going with a conservative OC of 860/625 because I use this box as my main machine and am able to pull about 369 MH/sec using GUIMiner/poclbm with the "-v -w 128 -f 1" flags.  Just unlocking those extra shaders bumped me up 5-10% MH/sec.

Using Catalyst 11.5's and SDK 2.4.

I'm sure I could probably go higher, but don't want to jack this card up :)

good thing because in getting 2 or 3 of these by monday :P

Just be aware, you may be able to unlock them but hit errors on some of shaders when you run the mining software.  I know the one I unlocked worked perfectly, but I can't guarantee all of them will or that they haven't physically cut the traces.

i bought two of these: http://www.newegg.com/Product/Product.aspx?Item=N82E16814127555

i can easily get over 400 mh/s. with that said i have not spent enough time to see if i can get over 425 mh/s.
i just turned them up and do not feel like paying attention to them over the weekend so i went slightly conservative.
they are a reference card. i unlocked the shaders but stuck with 6950 firmware.
i use msi afterburner software with the voltage enabled hack.
without logging into my win7 x64 box.. i put fans at 80%. voltage at 1190. mem at 520. i attempted to use
that ati control crap software to do the 20% increase boost but somehow i am not sure if it worked right. i need
to read up on it. clock speed just a tad less then 1000. couple of fans around the setup i had laying around. no case.

guiminer (newest version)/poclbm   -v -w128 -f 2

my speed is in my sig.. so just minus out my lame 8800GT on my PC i am typing from you see what I am running at.
the 8800GT is good for about 20 mh/s. So i would say the two cards are comfortably above 800 mh/s.

Have Sapphire reference of this card. I was unable to unlock shaders, but i was able to overclock it up to 915/300 with voltage 1087 and it heats up to ~ 76 C. Makes 364 Mh/s with -v -w128 -f 2 flags...

oh.. and do not forget to unlock that crappy sempron 140 to dual cores so you have something to
set those poclbm processes to affinity wise.. as in tie them to the unlocked core so your other cpu
is free to use as you see fit.

all i can say.. this felt like one big hack after hack tonight to get the most out of it.

What about your temps?

59 and 65 C respectively.

With puddinpop's rpcminer-cuda.exe I was getting 24, and with phoenix miner I was getting 30-31

How'd you manage to do that? Even after atiflash -unlockrom <deviceid> I still get "Cannot erase ROM" and it won't flash. Am I doing it wrong? Using just a modified version of what is on the card already. Perhaps it's my modification that's borked.

you are correct. i misspoke and currently guiminer shows 27 mh/s. the number i was recalling was
my attempt at using cuda which i thought would perform better and that was just not the case.

i really have to wonder if i should bother even using the 8800GT at home anymore except for brief
testing periods. Probably a waste of electricity.

It looks like XFX got wise and started write protecting the chips.  I won't bore you with the technical details, but at this point, unless you get lucky and are shipped an old card, the only way to unlock the shaders would be tophat flashing or physically bypassing a pin on the bios chip so that it doesn't send the info to denote being write protected.

The data sheet is at http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXuvyxs.pdf

It shows which pin controls this info.  The only question I would have is, would it revert to unset if that leg is cut/bypassed?  I'm assuming it would return null when queried... probably would fail spectacularly.

I went through the same thing, turned it off when difficulty jumped up around may 25th or so, turned it right the fuck back on when price skyrocketed up so high that I didn't give a shit about electric cost.

Just bought a $150 HD5850 to replace it tonight though, so I don't have any more PCI-E slots in which to place the 8800gt, so it now sits on my desk; its once hot heatsink slowly cooling down, probably never to warm up again.