I love my 290's, they are built like tanks and run stable. Small oc and you can get 29 mh easy
They are not that power efficient and are a bit loud but I have mine in the shop. If you have cheap power costs then they can be a good option, with a undervolt they consume about 220 watts at the wall. Reapply the crusty thermal grease and use a custom fan profile and they will run at decent temps.
Thanks for your reply. I am currently using a few Hawaiis, but they are all aftermarket cooled. do you own reference cards?