Try ditching sapphire trixx for MSI Afterburner. You may be very glad you did so. I sure was. That and giving up on messing with any voltage tweaks and especially Power Settings adjustments.
(3) 7950's
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T.C. = 24000 (24000 or less intense at 21056 21760 = all divide by 64.
W.S. = 256
I. = 20 (reduce as required to 19, or even 18 with too many stales when set higher)
@ 1015/1450 = 593 to 600 avg. khash/s
@ 1050/1500 = 610 to 625 avg. khash/s
Note:
Multiply the Memory Clock setting (1500) by 70% to get the proper Core Clock setting (1050) hence Core Clock = 70% of Mem Clock. At least that's what I recall and still use as my own guide.
Don't adjust overclock or anything else in Afterburner or trixx while miners are running/mining. Stop miners first. Then adjust overclocks. Then restart miners. Otherwise drivers damage and such, along with a crashed pc can result.
Don't run Afterburner and trixx both together. Nor any two apps at the same time that can monitor or adjust volts/overclocks, etc.
Dropping voltage too low can result in too much amperage, which can also fry things too. Hence why modern devices turn off all at once when batteries voltages get to a predetermined level. As volts fall amps rise.
Most cards are voltage locked as of of late.
Check with 50miner software's Overclock Tab, or something, to see what your voltages are in the case of locked voltage because Afterburner wont display volts on locked cards. I don't recall if trixx did or not either. Too high of voltage is even worse if you attempt to overclock too high (=fried cards).
1.09 to 1.16 volts is where to be voltage wise as far as I know if your going after Overclocking seriously. Not higher voltages, nor much lower either, unless you want to risk an unstable or barely stable rig. But I have read others dropping volts even lower, not sure how far they overclocked though.
7950 cards with boost switches or not hopefully fall between those two voltage settings (1.09 to 1.16 volts). Some cards on/off boost are running at 1.26volts or there abouts, way too high with higher overclocks and will result in extreme heat and high electric bills, plus maybe fried cards.
Best trick: the boost switch on some cards drops/raises voltage by large amounts. Pick the lower voltage setting. Then overclock. But leave the Power Setting at 0 (default). I wont push further than 1050/1500 myself. And I slow them down quite a bit when out of town, way down if gone for weeks. And I make certain the room stays at a reasonable temp. Of course I doubt it could ever be too cool, but below freezing would not be wise either. Nor would very humid air.
Overclocking is where the pay off is. Ignore bad advice, and there is plenty of that around these parts. They may mean well, but their either confused, or don't mean well at all.
With Afterburner one can toss a few cards in, even various brands with slightly different voltages, all being 7950's, and Afterburner will overclock sync all of them to the card you set it to be the master card. Too cool. And settings hold after closing Afterburner. Unlike Trixx in my own experience.
My experience was trixx wasn't the way to go. At all.
MSI Afterburner version 2.3.1 is very stable. Do what works, or experiment as you please but I stick with what I know is stable for mining purposes. After setting overclock close it all the way up, reboot, recheck it's holding the settings, then close it up again, and your good to go. Way better than trixx as I recall...
There is nothing wrong with AMD Catalyst v13.4 - works great for myself. But do what works for you and keeps things stable, reliable.
Use AMD Catalyst UNinstall Utility 1.2.1.0 if you run into driver issues and then re-install the drivers of your choosing. If your screen freezes during mining while overclocked, and/or you do hard shutdowns drivers may or may not get damaged. Realize that. Remember.
And remember beware. Some advice in these boards is not good advice, for whatever reasons. FUD, ect.
Adjust one thing at a time. Doing otherwise and you wont know what helped or hurt things until your more experienced.
Good Luck!
Last tip:
https://www.multipool.us/