I'm new to Ethereum mining, I bought a friend's mining rig and built a case for it. All the software is already installed, it runs on Ubuntu 14.04.
Its hardware specs are:
MB: H61 Pro BTC
PSU: Leta G1600
- 1 HD7970
- 1 R280X
CPU: Intel(R) Celeron(R) CPU G540 @ 2.50GHz
RAM: 2x4GB DDR3
Seems to mine fine, for the most part, except it seems to me like the hashrate is really low. With these two GPUs I get about 32MH/s.
I tried to do some troubleshooting, update the drivers. When testing with a single GPU I get 16MH/s out of either card, kind of far from the 24-25MH/s I see on benchmarks.
For a moment I thought this was due to the GPUs having been used for a year straight prior to that, but recently I bought an additional HD7970 from someone who used it for gaming (and gave it proper maintenance), still gives me 16MH/s. The three GPUs put together output 46MH/s.
Is there something I'm missing there? Is that a normal hashrate for a rig like this or is there an issue?