I run GUIMiner-Scrypt (trying to learn SGMiner atm). I was running the newest version out with the green and white icon. I have noticed the stales I produce far out weigh the accepted I have been getting for the last 21 days or so. This is only an issue on my 280x's and 290's. 1 5870 and 1 6970 both run fine with the newer version. I tried dropping intensity down, overclocks down and everything else I could think of.
I have been testing an older version I had on a flash drive from about a year ago for about 2 hours. The orange icon one. My stale numbers have dropped signifcantly so far. I am going to run over night this way to verify.
Does anyone else use GUIMiner or is it pretty much just me? If so, which version do you use and what cards and accepted/stale ratios do you get? I'd be interested to see if anyone else has this issue and if this is a solid fix for it.
Keep up the great work Terk! Remember; haters gonna hate!

Off to bed. My Norco is making me loopy (maybe that's why SGMiner isn't making any sense tonight)
And if anyone is interested -
https://bt.irlbtc.com/view/489404.msg5392264#msg5392264 so after a 14 hour test run I can report, so far, my stale rate went from over 55% down to 7-9% inside of GUIMiner. Also, my estimated payout showing on clevermining is substantially higher than it usually is at this time of day. To be honest, what it is at now is what I have been making all day and I am actually down 1 r9 290 atm (down 830kh/s). So switch to the older orange version and see if this helps you. I cannot find a version number anywhere in the folder it is located in so I am not sure how to identify it other than the icon color.
Happy hunting!