Just going back and confirming / correcting some assumed fixes.
For the S5 what is the recommended worker difficulty. I have been using 2048. Is that high enough?
1024 should be good enough. 2048 is probably too high.
The only difference you should see between 2048 and 1024 is more varied hashrate near the start before it averages out. Network load is negligible either way and both are still low enough that discards shouldn't be significant.
EVGA 1300 for 2 S5 or EVGA 1000 for 1 S5
What's the recommended power supply for an S5?
EVGA PSUs are quite hard to come by in the EU, and when they are their prices are really out of wack. A Corsair CX750M would be recommended as an alternative for 1 unit, and a CM1000 potentially for 2. Someone will have to test it first (I only have 1x S5) but I believe it should be okay due to the crazy headroom naturally on a CM1000.
Are you using four separate cables?
Separate?You mean each plug straight from the psu?No.I have 2 cables and with two heads each and one cable for one board.
Should i buy 2more modular cable?
Yes, you should have four cables. Pushing close to 300 watts in one cable is simply too much for most standard PCI-E cables. My guess is they are getting too hot and the PSU's thermal protection is shutting it off. If you feel the cables they are probably hot to the touch after the miner has been working a while. Each input to the S5 should be a separate cable. If the PSU has four separate PCI-E outputs you should be running a cable on each one.
Nothing wrong with 300W on a single cable [READ PCI-E CABLE not PCI-E connector. Its assumed that there are 2 PCI-E connectors]. Even 18AWG PSUs will do 400W almost inherently. 500W things will start heating up and is very boarderline, 600W is no go on 18 AWG.
Think of examples of this - ASICMiner Cube was about 330W on a single strand, Antminer S1s were ~300W on a single strand with COLD cables, ASICMiner Tubes were 440W on a single strand (with unusual PSU selection). PSUs with 16AWG can do significantly more.
