One thing is for sure, different shader amounts of different cards in one machine are not a good idea.

I can't for the love of god can make my 7970 work alongside a 7870 properly. The problem is NOT with the 7970, that hashes away 700-750 perfectly.

The issue is with 7870. It stops around 350khash, although when I set intensity in cgminer to 20, it'd reach 420ish, but then I get constant hardware errors. Hell, I even have HW errors ate Intensity 14, even on 13, if the shader amount is 2048, as specified for the 7970. Multiple shaders amounts tried, did not help.

The problem is, reaper works fine with only the 7870, it hashes 400 stable, but it resets the display driver every 20-25 minutes, maybe sooner. Can I raise stability somehow there? It does reset the display even on default clocks, when I'm not aiming for the best hashrate to be found... Intensity 19 and 20 seem to just kill the driver, although there is NO hw error with reaper, because it can handle the larger than 8192 thread concurrency.

I would not have a problem mining one card with cgminer and the other with reaper, but this reset thingie is not good. I am using 12.8 at the moment I believe, should I try to go for the beta drivers?

Any advices? Also, my peak performance on the 7970 comes when I'm 1660memory and 1000 core. Not lower, as most people experience :/

Also, did anyone undervolt 7870 and to what extent? I think 1.2 is a lot compared to the 1030 my 7970 can handle.

Temps are 49-51 for both cards, they are on water I'll try two reaper instances with two configs, but frankly, I like cgminer better, more information on screen and more easily configurable.

What I'd really wanna know is if PCIE slots might cause issues for the 7870 stability, or something like that. I have the best mainboard kind of that money can buy, an asus maximus extreme V with 5 pcie slots all capable of 16x almost.

I'm really uneasy about the 7870 resetting itself on higher intensity. Although I'll give the 2 instances of reaper a go.

If nothing helps, i'll manually overclock the two cards via the starter batchfiles and make a script that restarts the 7870 reaper client every 20 mins, or something like that. I'll lose a few shares, but better than not mining at all

For me, the 7870 crashes at 420ish khash with reaper every 20 mins. and it is NOT the overclock I am sure. What is your minimum voltage on 7870? Mine is not a Tahiti core, but a pitcairn one unfortunately :/ And no, i get GPU errors right away IF i set the intensity to anything over 13 in cgminer. No hw errors at all at 20 aggression in reaper, but it resets every 20 mins anyway.

Any ideas? With bitcoin, the 7870 hashes away at 430mhash without any issues or complaints. LTC mining on those 2 different cards of mine is tricky. BTC mining is not at all.

Oh and I'd stick to cgminer with the 7970 if possible, because I have a lot better hashrates on it than on reaper with the 7970 :/

Running .938v 850/1250. Found going any higher was pointless, dont get increased hashing.


When I'm using the rig: (About 260 and totally usable, HD playback and dual display)



I'm pitcairn too btw, RoyalKing 2GB.

Tried to game with LTC going, 5770 mining while 7870 running World of Tanks, performance was fine but the latency was terrible, too many packets to the pool.

Also a LoL player but havent been playing the last few months.

Me neither, too much time consumed building rigz 

You can set different config values for different cards in cgminer.conf.  Have it write out a config for you and you'll see how it's done.

Would CGminer allow me to raise the thread concurrency over to 16384 on a 2gb 7870, while the 7970 uses 8192 as thread concurrency? I know different intensity vlaues can be launched, that is fine. But in order to have 19ish intensity, i HAVE to raise the thread concurrency a lot. As far as I gathered, it is either shaders or thread concurrency that drives the amount of memory being allocated for certain intensity's without overwriting the already used ram data.

Can you give me an example of two separate configs for two cards please?

Raising GPU threads will not increase thread_concurrency indirectly, it just adds another thread calling the memory and working the ALU.  In reality the GPU scheduler seems efficient enough that by just setting one thread, we get pretty good values for hash rate (usually the same or better than 2 threads for all my cards).

For 7950 use reaper

By the way, found a workaround to tweak my 7870 to acceptable levels, it is now doing 410. I had to install the mining stratum proxy to not lose shares as I'd do with normal reaper.

The 7870 key as it seems was to set vectors to 2. And by the way, I had to reorganize the PSU pcie and sata-->6pin molex-->6pin connectors, so the 7870 gets one dedicated pcie6 from the PSU, not just the 5v Rail ones. Now stability seems okay even at 20 intensity, so the driver restarts as a hunch, were indeed because of power management.

I really don't think i'd want to go higher now with the 7870, it is undervolted to 1.1 atm, might go lower, memory is at 1450 and core is 970. This is neat now. Whoever might struggle with a 7870, just try this, it'll surely work.

Already got a tip in the jar )) Thanks!