That's on the 290, not the 280.  World of difference.  Great card but it sucks up some power.  Also I think it depends on the card.  Problem with my 280 I think is cheap card, cheap memory.  Got lucky with the 290.  90 bucks on ebay.

Re: old cards.  Wonder if clustering, like slurming them would make any difference.  

ETA: google up Stilt's comments on 280/x cards, I think the original post is at the overclockers forum but it's been copied a bunch of places.  A lot of those things apparently were made quite cheaply, and just can't keep up.  On top of that it's hard to do much with the ROM's.  If you get one with elpida memory, it won't need much if any work.  Mine had a mix of hynix and elpida, flashing it didn't do much. Pushing the clocks just makes it worse.   My MSI 7950 crushes my Sapphire 280; had to flash the rom on the 7950 (hynix) and it likes the GPU clock at 1100.  For those who are having trouble tuning their 280's, might be worth running it thru GPU-Z and see what ya got.  Hynix isn't necessarily bad but can be.  Stilt says look at the sensors; the cheap cards only have a few basic sensors.  Some of those cards are just duds, I think. Mine sure is. Sgminer works right out of the box, with little to no tinkering, on my good cards.  No amount of tinkering has done anything for that frickin sapphire.