6990m Strange Issue

At least I assume it's my video card (could be something else I suppose).

Here's the background:
I recently re-installed Windows on my M17x R3 (I got a new 500gb SSD and set to AHCI in BIOS; was previously RAID). Despite it running perfectly beforehand, I've now been having issues with my 6990m.
To be more specific, the initial driver install seemed to be ok*, however the next day when I booted it up, I was getting odd patterns of polka-dot pixels in certain areas of my display!
I tried every driver I could find to fix it, but eventually gave up and just disabled the video card in Safe Mode to force it to use the integrated video card. This eliminated the "speckling" although obviously this is not what I would consider a solution...
I was at wit's end and decided to start fresh again so I re-installed Windows. This time I used the original drivers supplied on the resource disc and installed the 12.4 update on top of that (although I'm not convinced my card actually had it's drivers updated; and when I attempted to make it update by directing it to these drivers it wouldn't on the basis that the current drivers are "up to date"). I played Skyrim with perfect graphics for a solid 4 hours that night without a single issue, but the next day when I booted it up, the "speckling" came back the same as before.
I've since noticed that I can fix the problem by re-installing the drivers from the disc, and re-booting. This fixes it with a 100% success rate, until the next day of course when I start it up again and I'm greeted by patches of rainbow-coloured pixels.

*Intel 3000 and 6900 Series Video card showed up in Device Manager and GPU-z, though CCC was misbehaving and I couldn't switch graphics.

Does anyone have any idea why this could be happening? I know it doesn't make much sense but could the switch from RAID->AHCI be messing something up (I only suggest this because it was working fine for a long time before I changed this) or would that be a waste of time?
I'm a bit tired of re-installing Windows so I'd really appreciate a bit of advice here. Is it worth my time setting it back to RAID and re-installing Windows again? And should I just leave it with the original drivers or can someone suggest the most recent rock-solid stable one I should use? It's worth noting that for me, CCC and switchable graphics are absolutely not necessary, so long as the 6990m works I'd be happy enough having it as the single GPU.

Thanks in advance for any help...

 

Bump
Might be time to try another format I think...

 

I don't know if this might help ..
few days back I was having heat issue with my 6990 so I opened it it to clean the fans and everything ..
after that I notices some of the symptoms you are undergoing ..

opened my lap again and rechecked everything in place tight and the symptoms disappeared ..

reinstalled the dell driver and the 12.5 based on slickdude recommendation from here

AMD Catalyst 8.97 18 April – 7900 MOD – BenchmarK3D

and everything is perfect since then ..
I hope this helps

 

Check your temperatures with HWMonitor or HWiNFO. Additionally, check the event viewer and look for any warnings.

 

Switched back to AHCI and did a format and everything seems to be working much better now (touch wood). I don't see how these things are related, but all I know is it's working and that's good enough for me!

 

Apologies for bumping an ancient thread, but I felt it might be worth posting in here to close this thread in case some other persn stumbles upon this one day.

The problem was not fixed (in the long term) by anything I can point my finger at. Oddly, my eyes eventually adjusted to the multicoloured pixels all over my screen so well that I literally only ever noticed when other people would ask me what was wrong with it!
And so that's why I have no idea what fixed it. I haven't had this issue for months now and the only slightly reasonable/logical explanation for its spontaneous fix would be a driver update, I guess (or maybe a Windows Update?). In general, Windows 8 doesn't seem to co-operate with any Alienware stuff very nicely at all.

I did disable the IGP a long time ago, though that didn't solve the problem.