Originally Posted by SlowSpyder
At 1.15GHz my 7970 is bounching between 665 and 675MH/sec with no extra flags. With something there I can probably squeeze a bit more out of it.
I use GUIMiner. 1150mhz with flags -w 256 -f1 gets me 680 Mhash/sec. A single 6970 at 880mhz GPU did 390 Mhash/sec using -v -w 128 -f1
thilanliyan, if your 6950s can't be unlocked, I'd sell them and get a single 7970.
1) One of your 6950s is 1GB. Thus, the performance in future titles will be worse than it is with HD6950 2GB CF, which itself is slower than an overclocked 7970.
2) Not all games scale well with CF. HD7970 GE should be about as fast as an HD6990
, sometimes faster. HD7970 > 1.05ghz would be faster in most games, especially once HD8000 series comes out and AMD focuses even more on drivers for HD7000/8000 and most likely starts to pay less attention to 5800/6900 series (which may introduce more scaling issues with CF for older cards).
3) Those 6950s may lose even more value if NV launches GTX660/660Ti at aggressive $249-299 price levels and those cards force price drops on 7850 to $199. Now is the perfect time to sell the 6950s imo, esp. since 7970 has had 2 rounds of price cuts.
I think it also depends how much you can get for those 6950s and if they are unlocked into a 6970 (which should add to resale value) and have some warranty remaining.
The other possibility is to mine with 6950s for 5 months or so (until BTC block value drops from 50 to 25) and then get an HD8970 in 2013. If you unlock the 6950s and overclock them to 880mhz, that would make more bitcoins than a single overclocked on air 7970. Because in the next 5 months, 2x 6970s will make more BTC at easier difficulty level, you may be better off making as much as possible with them:
HD6950 @ 6970 speeds x 2 = 390 x 2 = 780 Mhash = 13.62 BTC x 0.95 (assume 5% fee, i.e., BTC Guild) = 12.94
HD7970 @ 1150mhz = 680 Mhash = 11.87 BTC x 0.95 = 11.28
So 2 x HD6950 @ 6970 will make about 1.66 BTC / month more. Let's make it simple and average it to 1.5 BTC x 5 months (to mid-Dec when block value should drop from 50 to 25) = 7.5 BTC @ ~ $7 rate = $53.
So basically if you think 2x HD6950s will drop in value more than $53 and you think HD7970 will drop less than $53 from today's prices by December, it's better to buy the 7970.
If you think 2x HD6950s will drop less in value than $53 and you think HD7970 will drop way more in value than $53 from today's prices, it's better to keep the 6950s.
If you think BTC value will increase from $7, then it's also better to keep the 6950s @ 6970 speeds until December.