Homwer:
Coupla things.......
1. Anandtech published a nice article on the topic. Though it has more of an impact on minimum frame rates than average frame rates and lower CAS seems to have more of an effect than speed.
http://www.anandtech.com/show/2792/12
22.3 % (SLI) increase in minimum frame rates w/ C6 instead of C8 in Far Cry 2
18% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in Dawn of War
15% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in World in Conflict
Even the bit-tech article shows the fastest performance at the CAS 7 1866 modules. The on game which they tested with showed the CAS 7 at 4.5% faster than CL9 DDR3-1600. CAS 7 DDR3-1600 is $40 more than the lowest price CAS9's. That's amounts to:
$2000 system - 2.0% increase in system cost
$1600 system - 2.5% increase in system cost
$1200 system - 3.3% increase in system cost
$1000 system - 4.0% increase in system cost
So even in a $1,000 system, you are getting more performance per dollar with the CAS 7's.
I use these CAS 7's in a lot of $1500 builds (no issues to date)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820226178
Tho some users ask me to use these 2133 CAS 9's instead
http://www.newegg.com/Product/Product.aspx?Item=N82E16820226199
2. The DH-14 does real nice on the older LGA 775 chipset (frostytech.com's platform of choice) but who's buying those CPU's these days ? The LGA 775 has a completely different heat signature than 1155/1366 so I'd look for reviews on those platforms. BMR (who tests using 1336 platform) putsthe DH-14 in the 2nd tier as far back as November. Even the Scythe Mugen 2 which is half the price beats the DH-14 by 1C
http://benchmarkreviews.com/index.php?option=com_content&task=view&id=447&Itemid=62
If ya wanna spend $80 and up, I'd look at the V6 GT ..... It's the top cooler tested to date at BMR except for the Antec Kuhler 920 which is a self contained water unit. Both however, are quite loud. If dead quiet is your goal, the Thermalright Silver Arrow or Archon are excellent choices.
http://benchmarkreviews.com/index.php?option=com_content&task=view&id=674&Itemid=62&limit=1&limitstart=4
3. Given the $$ spent on other parts of the system, I'm surprised at the choice of the 6950's. I am assuming a 1920 x 1200 120 Mhz monitor and at that resolution, I'd be choosing the 900 MHz 560 Ti's (862 fos in SLI) over the 6950's (759 fps in CF for the OC;d Frozrs)
Guru3D uses the following games in their test suite, COD-MW, Bad Company 2, Dirt 2, Far Cry 2, Metro 2033, Dawn of Discovery, Crysis Warhead. Total fps (summing fps in each game @ 1920 x 1200) for the various options in parenthesis (single card / SL or CF) are tabulated below along with their cost in dollars per frame single card - CF or SLI:
$250.00 6950 (479/751) $0.52 - $0.67
$290.00 6950 Frozr OC (484/759) $0.60 - $0.76
$210.00 560 Ti (455/792) $0.46 - $0.53
$355.00 6970 (526/825) $0.67 - $0.86
$220.00 560 Ti - 900 Mhz (495/862) $0.44 - $0.51
I been having great luck with the Asus ENGTX560 TI DCII TOP/2DI/1GD5's getting almost all of them to OC to 1000MHz w/o any voltage adjustment whatsoever. Given the over sized coolers provided, no temp issues either.
However, if you go w/ a 2560 x 1600 monitor, I'd do the 2 GB 69xx series.