Hey guys, just joined today because I can't seem to work out the problems I'm having with my non-dedicated scrypt mining rig. I hope someone here can point out what I'm missing.
So, the situation: I only got into mining crypto currencies very recently, all I've mined so far are COYE, LTC and 42 on a GF 560 Ti 448 @ around 225-240kh/s.
Of course I wanted more so I bought
3 new Sapphire Boost 7950s from two different retailers and one x16 powered riser, and I was going to buy new hardware for a dedicated rig but right now I don't dare to until I can say for sure what the problem is.
I'm running an
i7 970 Hexa on a MSI X58 PRO-E SLI (also supports Crossfire/X, newest BIOS.. from some time in 2011 iirc) board with
3 x16 slots and 24GB of RAM, using
7 x64, with plenty of ventilation for my usual needs and a CoolerMaster Real Power M
850 power supply.
The PSU supplies
12V on 6 rails: rail 1,2,5 and 6 supply
18A each, rail 3 and 4 supply
28A. Rail 3 and 4 are only connected to the two PCI-E 8 pin connectors, 5 and 6 are for the two PCI-E 6 pin connectors and 1 and 2 are for CPU and mobo, at least according to the manual.
I'm running cgminer-3.7.2-windows using "cgminer.exe --scrypt -o stratum+tcp://...:... -u ... -p ...
-I 12"
That's the only intensity I can run, regardless of which of the 3 cards I use, regardless of whether I use two 6 Pin Connectors or 2 8 Pin->6 Pin Connectors (rail 3&4) or a mix of both. Everyone else seems to be running -I 20 on these GPUs and
getting 550-750 kh/s, I'm stuck at 245... if I try to raise the intensity even just 1 step things go crazy with
hardware errors, on all 3 cards, no matter which one I try, and the WU/m go down dramatically.
I have tried the following drivers/SDKs:
- Driver 13.12, SDK 2.9 => initially installed; can run -I 12 at most @ 235kh/s/GPU.
- Driver 11.6 => can't detect GPU/install driver in Windows
- Driver 11.12 => can't detect GPU/install driver in Windows
- Driver 12.4, SDK 2.7 => same as 13.12
- Driver 12.8, SDK 2.7 or 2.8, not sure anymore => same as 13.12
- Driver 12.10, SDK 2.8 => 5% faster (235 kh/s => 245 kh/s)
(I've used Guru3D's Display Driver Uninstaller to remove the garbage between installs and from the old Geforce that was in there once)
I've also installed a
2nd 7950 at the same time (w/o Crossfire bridge) and curiously enough they
both behave exactly like a single one does making me think it's probably not a power supply issue, they both work only at -I 12, both produce 245kh/s, both have a few HW errors, 10 per hour maybe, didn't really count. WU around 200-250/m each depending on mood it seems.
They're both connected using one
8pin->6pin cable from the 12V3/12V4 lines (28A each) and one 6 pin cable (18A each).
So I'm leaning towards the motherboard being the culprit. FYI it only supports PCI-E 2.0 but that shouldn't be a problem right? I know it's a really old motherboard but my PC is running quite fine on it, except for this mining business.
Like I said, I want to buy new hardware for a dedicated mining rig anyway but until I can be sure what's causing this I can't afford to potentially throw away even more money.
Oh yeah, and I haven't tried the riser yet because I can't imagine it helping much when the board is able to power 2 cards apparently without problems.
And I forgot to mention I also tried slight (+/- 100MHz) over- and underclocking, not touching any voltages though, with no noticeable changes.
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As for the new hardware, I'm on the fence between taking the cheapest, most low power solution possible or paying a few more bucks and getting something that can still be used as a PC on the side, or if I turn out to be unlucky or too stupid for mining. So I'm thinking either Sempron 145 and ASROCK FM2A88X Extreme6+, or AMD A6-6400K Black Edition and ASROCK 970 Extreme4 (AM3+). I haven't thought too much about the motherboard though, I just think I'd prefer one with 3 x16 slots so I can install the highest and lowest card normally and just take the middle one out using a riser to keep everything coolish.
Then RAM, I always hear 4GB are enough but the cgminer readme states you should have enough RAM to match your VRAM, so I'd need at least 8 (or actually 9) GB right? So which is true?
I'm entirely open to any suggestions here, no components are nailed down yet, and as for the PSU I'm leaning towards a 1000W Corsair for ~150€ or a 1200W Be Quiet or Superflower Platinum for ~225€.
Sorry for the long wall of text, I just wanted to explain what I tried as best I could.
Thx in advance for any suggestions and better luck mining than I had so far
