SuperPi on GPU, were going CUDA

[Lightman]

What 290x's are you guys using? Some cards with Elpida memory will score poorly due to broken memory clock tables in the bioses and pushing clocks too far will result in the same.

for example my sapphire with stock bios and elpida memory gets about 24 seconds.

Yeah, mine is Elpida so this is the differentiator.
When I was mining my R9 290 Hynix card was faster at it with lower clocks than my full R9 290X. I had to run R9 290X @1500Mem to get same hashing speed as Hynix card with stock 1250MHz memory (which didn't OC at all :P).