1. Try single PSU, start with single GPU, check power consumption AT THE WALL for each GPU.
2. Check all you GPU maybe you have faulty one.
3. Next step - proper biosmod with downvolting, you will be able to limit you power usage to 100W per GPU with hashrate about 900 H/s
4. Add one GPU at time, check power consumption AT THE WALL. Go up to 600W at the wall, no more. Expect to get up to 4 GPU running. No significant hashrate drop should be expected.
5. Use second PSU to power up riser and powerconnectors of next GPUs, again one by one. Check power consumption AT THE WALL at each step. Do not change wiring of the first PSU, switch on the second PSU first step and only then start the first else you can have issues with GPUs connected to second PSU.
6. if you will fully utilise (up to 600W at the wall) two PSUs follow the same procedure with the third.
7. Biosmod is recommended but not mandatory, but expect much lower hashrate with much bigger power consumption.
8. 20 Gb pagefile may be a bit small if you have 8Gb GPUs
my bad. I omitted the rig is comprised of the modules and the behaviour is the same even with the main unit alone. I'm talking about a single PSU powering up the motherboard and 4 GPUs.
I can't seem to squeeze more than 630 h/s per single card, even when Claymore miner is fired up with a single GPU so it's my assumption that there is something wrong at some other level.
with downvolting and clocking (software via claymore parameters) I've been able to drop to power consumption but this is not the main issue here, that is making it mine more.
What is the logic with paging file? I've tried adding an additional HDD and assign a 100 Gb pagefile but I haven't noticed any improvement on stability or performance whatsoever.
You can't get much from AMD RX GPU without BIOSMOD. It's not that hard :-). Lots of guides for basic bios mod that is usually enough for mining. The strange thing was that you have degrading hashrate when adding cards. I guessed that it can be due to overloading one of your PSU's due to uneven power distribution. You still may be overloading one PSU with 4 cards, each can draw up to 200W before bios undervolting.
As of paging file - no gain in performance for big paging file. If any problems arouse I try to use safe side - paging file size = (number of GPU)X(GPU memory) + RAM size. It is overkill just to be sure you are not getting any initialization failures due to small paging file.
