No Signal from HDMI port

[BarnaclePete]

Hello,

I have about 25 HP ProDesk 600 G3 Microtower PCs at a school hooked up to projectors through a 75ft active HDMI cable.  On about half of them everytime the projector is powered off and then back on they come back with a screen that says "no signal."  The only fix we have found is to pull the HDMI cable out of the port on the PC and then put it back in.  It seems to be inconsistent and sometimes it will be fine and then one day it will lose the signal.  Previuosly the same machines were in a different school hooked up to the same model projector, but with shorter regular HDMI cables and there was no issue.  I have tried updating drivers, but there was no difference.  I have also tested the HDMI cables with a laptop and there are no issues.  Has anyone seen this problem before?  Ideas on a solution?  Best thing I can see is possiblly the computers on board HDMI port is not compatible with the active cables.

[TheOldMan · Accepted solution]

Running 75' for HDMI cable to projector is more than likely the cause, even though they are "active HDMI" cables.  It is most likely just on the edge of providing enough signal strength to trigger the HDMI picture and any slight impedance to the signal strength will cause a "no signal".  Is there anything in the path other than going directly to the projector?  Also, assuming these cables to be new, since this is in a different location than previous, are they all the same brand and type cables?