Why is the 6770 such a poor performer?

[bcpokey]

Was browsing around at cards, and noticed the specs for the radeon 6770 lists it as having 320x4 stream processors clocked at 900MHz at default. This compared to say a 5870 which has 320x5 stream processors clocked at 850MHz. As I've been told that SPs are more or less what makes the hash happen, a quick calc puts a 6770 at 80% of the hashing power of a 5870, or around 330MHash/sec. Why then is it that it looks to be pulling barely 200MHash/sec from the hardware lists?

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[MaGNeT]

As far as I know, the HD6770 has only 800 stream processors, while HD5870 is having 1600 of them.

[bcpokey]

Ah, I guess the article I was reading misquoted the number of SPs, that'd make sense then.

[bmgjet]

open up gpu-z and see how many it has.
If where you bought it from stated how many SP it had and was wrong that could be a reason to return it and get another card.

[grod]

6770 is the exact same hardware as a 5770, which has the same number of shaders as a 4870.   That being 800.

[tunatime]

never uesed a 6770 but i have had one of my 5770 clocked at 1050 core pulling 230mh/s not bad for a card i bought for $60 usd uesed a year ago