The RX580 cards in my rigs are not reporting temps or fans to Claymore when nothing is plugged into any of the display ports of the cards. My 1070 ti cards don't have this problem and correctly report fan speeds and temps regardless if there are HDMI dummies plugged into the cards.
I have tested this twice now with the same issue.
When I plug the HDMI dummy into one card and remote into it with RDP Claymore will not show fan speed or temps in the console or from another computer via Claymore Manager. Even if I restart Claymore the stats are not displayed. I then close RDP and VNC into the rig. When I start up Claymore I do get temps and fan speeds. Claymore Manager also report the speeds. But Claymore then constantly restarts because of memory errors. I do have overclocking set pretty high and the RX580 cards are mining at around 31.65 - 31.70 mh/s each.
I then close the VNC app and remote back in via RDP. When I then start the mining software my UPS errors out because the cards are drawing more power than they should. They are also mining at lower speeds, around 30.5 mh/s.
The only solution I have is to remove the HDMI Dummy and reboot the rig. When it first happened a few weeks ago I did not realize what was going on and ended up reinstalling the drivers. However it appears not to be necessary and once the dummy is removed and the rig rebooted all is fine again, except I can't see the temps / fan speeds.
I installed Awesome Miner and that does allow me to get those stats from the rig but you have to go through a bunch of steps for each rig to get the data. It would have been really great if Claymore's Manager could report these stats without the use of a dummy.
It seems the 4k dummy places a lot of stress on the card because it now thinks it should display an image. Not sure if anyone else has noticed this. I think you can go further with overclocking when the cards don't have any monitors or dummies plugged into them.