Dell 3040 - User using it, then monitor goes into power save mode

Had some Dell 3040's rolled out last year. Have had 3 of them play up in the last few weeks.

User is happily using it, then the monitor suddenly goes black with message "Entering power save mode".

User usually has to power off PC, then finds sometimes they still can't get a display again.

I've seen this problem strike myself last week, whilst using it myself when investigating. Unplug and re-plug the DisplayPort (DP) cable *may* get your display back. Swapping a monitor *may* get your display back. Leaving it off for an hour or so *may* get your display back. Albeit temporarily.

Ok, I was told by Dell a while back to update BIOS and latest drivers, such as video, but that is not a solution.

Swapping monitors and the DP cable is not a solution (PC's do not have VGA or DVI ports).

When it did this to me last week, I replaced the DP cable and got my display back. But the downloads I was performing had stopped during the time the monitor was in power save mode, so looks like it's the mainboard at fault.

You run the Dell diagnostics and it doesn't find any hardware faults.

Dell have however, replaced a mainboard on one (or possibly 2) of them, and it still had the problem again.

It's rather annoying when you log this with Dell and the technician says they haven't heard of this problem before.

Anyone got a definitive answer as to why this happens. I am happy to gamble my life's savings that I will see this problem again this year.

Dell 3040, Win 7 (could be 32 or 64 bit), Dell monitor connected via DP, on latest BIOS (1.5.3) and latest drivers that Dell Command Update has detected and installed. We've found swapping monitor and DP cable with another PC proves the fault is on the PC.

Thanks, DV :-)