Robert,
I'm having the same flickering issue, but for a different reason.
Here's my setup:
Gigabyte GA-Z77X-UD5H rev1.0, BIOS F16c mod3 includes the latest and greatest Intel stuff
Intel MEI FW v8.1.40.1416 + MEI driver v9.5.3.1520
2x 4GB Kingston HyperX Blu DDR3 @ 1629MHz, 9-9-9-24-1T, 1.65V, Dual ch mode [previous]
2x 8GB Kingston HyperX Beast DDR3 @ 2240MHz, 11-12-12-24-1T, 1.6V, Dual ch mode [current]
Core i5-3570K @ 4.17GHz (1C & 2C), 4.07GHz (3C & 4C), BCLK 101.9MHz
Stock Intel CPU fan + one front chassis fan
HD4000 GPU running at 1.35GHz (default is 1.15GHz).
Win7 Pro SP1 x64 eng running on Intel 520 120GB SSD
WD 500GB 7.2K HDD SATA3 - mainly used for video storage
2x LG IPS236 23" LCD monitors, one via DVI, the other via HDMI, both running at 1920x1080.
Intel HD 4000 driver: v9.18.10.3186
NOTE: I live in Israel, a 50Hz country (if it makes any difference).
Just to give you some understanding, I consider myself a computer expert, and worked as a laptop, desktop and server technician for many years.
Now to the flickering issue:
I'm experiencing flickers that occur for a fraction of a second, at a frequency of about once every 30 sec or so (it seems random, actually), mainly when watching video footage, but not only. A flicker might appear on one monitor and then on the other...nothing that seems systematic, anyway. Everything continues to work as normal, except for these split-second flickers/glitches.
I have been watching HD, Full-HD and 4K footage (in various frame-rates) on both my monitors simultaneously for the past year without any issue what-so-ever. The HD4000 graphics has been rock-solid and I always update to the latest driver and/or BIOS firmware. As you can see from my PC specs, I'm over-clocking the CPU, GPU and RAM to eke-out as much performance as possible from this system.
Temps were monitored through HWinfo, GPU-Z and other apps - all temps are in check and well under the limit (up to 75° Celsius in most cases).
A couple days ago, I've upgraded the RAM from 2x4GB Kingston Blu 1600MHz to 2x 8GB Kingston Beast 2133MHz kit, which not only doubles the amount of RAM, it also runs faster. This was mainly to help the HD4000 GPU achieve better video memory performance, especially when playing-back multiple high resolution videos at the same time.
I've allocated 1024MB in BIOS to the Intel HD4000 GPU - again, to help it as much as possible to achieve high performance.
Windows 7 Pro x64 is updated regularly, and protected by a good Symantec AntiVirus.
Basically, both monitors exhibit an annoying flicker which did not happen with the previous Kingston 8GB RAM kit. Of course, I still have this kit and can put it back in, but I really don't want to, as I can see a performance difference with the new 16GB kit.
I have checked the Intel graphics settings, and made sure both monitors are set to 60Hz.
Multi Display Mode is set to Extended.
I have checked the DVI and HDMI cables, and even replaced them with new ones - but the flickering still persists.
I also tried replacing the HDMI with a VGA cable, just to see if a different video input has any influence on this issue. No luck.
I've toyed with BIOS settings, and brought the RAM into spec clocks - to no avail.
I'm pretty sure this flickering issue is caused by either the graphics driver or graphics firmware in BIOS (SVGA BIOS). Probably an incompatibility with the higher RAM clock, or something of the sort. Other than the occasional flicker here and there, especially noticeable when playing videos, everything looks good.
I'm pretty sure the 16GB Kingston RAM kit is working properly. I Intend to run a full memtest on it when I have time, and even-though the flickering issue started after this RAM upgrade, I don't think the RAM is the culprit here.
I haven't tried adding a PCIe graphics card, as the HD4000 is performing admirably. I do have a brand-new GeForce card lying around, but I don't really need it.
I'm even experiencing flicker right now as I'm writing this (on Google Chrome)!!
Please note that:
1. I don't want to go single channel with just one RAM stick.
2. I really need 2 monitors, and don't wanna use only one.
3. I'm pretty sure the BIOS I'm using has the latest MRC on it, but I haven't checked (how do you check)?
Please help resolve this issue.