Ok, so first off I have a 3 Vega 56 mining rig that is running the old version of XMR-Stak AMD. This new version for some reason isn't optimizing Vegas.
Now for my Asus R9 290 in my gaming PC, it is a different story. I am now getting 1183 h/s on my R9 290 and 145 h/s from the CPU.
I was trying to find a way for my gaming PC to mine without having to run blockchain drivers for AMD. I am running what I believe is 17.7.1 driver which is stable and doesn't crash my computer. Which if you have an R9 290 you may have experienced when updating drivers with this card, understand how painful it can be. Then gone back to this driver or another stable one, like me.
Driver link: http://support.amd.com/en-us/download/desktop/previous/detail?os=Windows%2010%20-%2064&rev=17.7.1
I was attempting to get this card to do like 780 h/s on Monero and kept getting like 400 h/s-550 h/s and crashes when I tried to change the settings in GPU tweak, wattman, whatever i tried it kept crashing.
Then I just decided that was the best it would do. I was using XMR-Stak AMD and trying to mine Aeon. Must have missed that my hashes were getting rejected by the pool, and then downloaded Aeon- Stak. Couldn't find the EXE file, and people said XMR-Stak 2.0 worked well and had a currency configuration of Aeon or Monero at launch so I decided to go with that.
Link for XMR-Stak 2.1: https://github.com/fireice-uk/xmr-stak/releases
Then I found out there was a new XMR-Stak 2.1 that launched a day ago (from yesterday when i set this up), now 2 days as of writing this. I decided to go with that. Did no configurations, just entered my wallet info and pool info. Boom!! I am getting 1183 H/s from the R9 290. It was incredible. I was ecstatic. I told my wife, she didn't care. Today I told people on my slack and in my Monero pool. Some didn't understand how this could be, but it is. All stable at 70 degrees Celsius, been mining for about a day now.
One R9 290 at 1183 H/s great success, as far as I am concerned. So for older cards I suggest going after Aeon.