Have Optiplex 3040 about 1 year old, video HDMI and DP with HDMI adapter running two monitors. First problem noticed was slight keyboard lag when typing, change keyboard, same problem. Then about 3 months ago, video corruption, screens turning off. Did all the update drivers, bios update, switch monitors and cable dance, no solution. For example each monitor with same cable worked as second monitor on Dell laptop.
Call Dell under warranty, came to office and replaced mother board. Ok for about a week, then one monitor cutting off, then screen corruption started up again, but no keyboard lag. Concluded the Intel 530 graphics is a problem. Bought Radeon R7 250 2 GB video card, too big to install. Took off fan shroud and fan, use low profile bracket and install. No heat problem, running business apps only, one week so far and no problems at all.
I have a similar issue with my Optiplex 3040, core i3 work station. I am trying to extend the the display, but things are not working. Only the monitor with DP -DP connection (Monitor 2) is detecting all the time, the other one (Monitor 1 ) is unable to detect. Here is my configuration :
HDMI (OUT) DP (OUT)
HDMI (Male) to VGA Female DP (IN) DELL monitor 2
VGA Cable(MALE to MALE)
VGA (IN) Dell Monitor 1