i made some tests and it showed that a old 5870 is almost as efficient as R9 270 (200 KH/s scrypt-n). Lyra 2 uses half the power of n scrypt, so i think it doesn't matter if old or new gpu is used.
But yes, i forgot -> whe don't know the hashrate this cards do on lyra2re.
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All,
I get ~1.15 MH/s on Sapphire R9 290 Tri-X OC.
There also was a guy who did 1.1 MH/s on R9 280X i remember...
He must have oc'd the 280x 1150 or higher on the core and 1500 on mem at least, maybe.
Scyrpt-N is really power hungry type of algo because the huge memory requirements. Have anyone did a power efficient test yet, ie. kill-a-watt meter?
Cool, guess a 6950 will do about the same as a 5870 and a 6970 will do a little bit higher than a 5870.
I get on my 290x (1030/1250 stock msi gaming) 1.3MH/s average.