al4x the 6990 is nothing more then a CF-ed set of cards on a single board... So whatever problems you seem to have with a CF setup will probably still be there with a single dual GPU like the 6990... What problems are you having with your 6950's ? Also your system specs show 6970's ? did you flash the 6950's to 70's ? Tried running them back on the stock BIOS ?
I still think some people in the future are going to face some funny things happening to their flashed 6950's to 70's, the real 70's have for one better memory and better power circuits with an 8pin power supply too. Maybe the problems you are facing are related to the Flashing ? Like I said try them on the Stock BIOS 1st and Default settings..
The memory is the same in general, Samsung/others tend to simply make the same memory and sell it off at various different costs, more often than not binning is just not worthwhile there just isn't the market for the highest end memory.
As for power, 8pin provides exactly 0% more power than a 6pin pci-e cable, the card accepting different amounts of power due to different settings is another question altogether. As for power circuitry, nope, FAR better quality VRM's that are a lot more efficient and a LOT cooler running than the 5870/50/5970.
Of course some people will have problems, some people who don't flash their 6950's will have their memory die, or core, or the vrm's, thats life, things break.
In reality theres just hugely less demand for higher end stuff than the cheaper version of it, has always been the way, a 6950 is going to rarely be a failed 6970, a 6970 is most likely just double checked it can run at full.
Lets say you make 10,000 wafers with 100 working cores on a wafer. Normal sales distribution is say 80% as 6950's and 20% as 6970's, is it cheaper to test 100% of cards and only sell the best ones as 6970's, or test around 20% make sure they can run at 6970, then test another 5% to cover any that don't make it.
Memory goes the same way, Samsung see the chance to sell the memory slightly higher but AMD only need 2% of their gddr5 at that speed, is it worth running whole batches of better more expensive memory or just test a few % of the normal memory and double check its ok for the higher speed?
GiT as for the price vs worth, it will be cheaper than 2x6970's, probably a little more expensive than 2x6950, but faster, so offer better value than either setups, vastly better value than a 580gtx, and plenty of people use xfire/sli on top end cards where the combo costs more than a 6990 will.
Theres also plenty of games that do bring computers to their knee's and 3d/eyefinity setups that desparately need more power.
