I've been dealing with this issue, since I set up my Lenovo H520 with IB i3-3240, 8GB DDR3-1600, and a 1TB HDD. Installed a NAXN 350W, or maybe 400W PSU, and an HIS 7790 1GB GDDR5 card. OS is Windows 8. Monitor is 1920x1200 24" IPS Auria.
Using a 10ft HDMI cable purchased from 1sale.com.
Not having any sort of display or cable issues when monitor isn't in sleep mode. Nor am I having any issues upon cold power-up.
I will note that I run BOINC in the background, which "crunches" on both the CPU and the GPU. What that does when the PC goes into monitor-sleep mode I don't know.
I noticed that when it won't wake up, the HDD light is flashing, so it's not hung, the PC is still processing in the background. However, I cannot shut it down normally by pressing the PC's power button. It seems to do nothing. Nor does the button on my keyboard that shows a power symbol.
I have to hold down the power button and force a hard shutdown. Then when I reboot after doing that, the wireless card won't activate, so I have to do a restart to get the wireless back.
Edit: Oh yes, forgot to mention, NVidia for me from now on. Done with AMD's shoddy engineeering.
Btw, I previously had two of these cards, and I was crunching with them on an ASRock 990FX Extreme 4 board with a Thuban 1045T CPU, 16GB DDR3-1600, and Windows 7. Variously on BOINC, and F@H. I had the same problem on that system. I figured it was just the system, but it has to be either the cards, or the drivers.
I will also note, that on the Lenovo i3, it previously was waking up ok last night, but one time, the screen was just black with a mouse cursor showing (didn't put monitor to sleep properly), and other times, when I woke it, all of my desktop windows had been resized to something very tiny, and were all in the upper-left corner. So the desktop workspace had been massively shrunk down for some reason. (My HDMI-connected monitor is my only display.)
Edit: This is with a fresh clean install of 14.4 WHQL drivers.
Edit: Other weirdness. Sometimes, instead of turning the monitor off, I would get a black screen with a white mouse cursor arrow that I could move around, but moving it didn't cause the screen to come back. Turning off the monitor at that point, and then turning it back on, caused the screen to go into standby again.
Anyways, I recalled having a similar issue back in Dec. of 2013, during the DC forum's F@H race, when I was using the beta drivers. I remember rolling back to the 13.12 WHQL drivers and it fixed the problem. So I tried that again.
So far, in a day and a half almost, no problems waking from monitor sleep mode, even with BOINC crunching on the GPU in the background.
Also, the desktop windows don't get resized down to tiny windows when it restores, the whole desktop stays put.