The 660 Ti is a great buy and the MSI PE has "secret sauce" in their BIOS.
http://www.techpowerup.com/reviews/MSI/GTX_660_Ti_Power_Edition/33.html
What I find surprising is that MSI's card is faster than many other GTX 660 Ti cards reviewed today even though it's running lower base and boost clocks..... It seems that MSI has added some secret sauce, no other board partner has, to their card's BIOS.
Asus's new BIOS on the DCII edition has also added this secret sauce and I expect other manufacturers to follow.
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=-1&IsNodeId=1&Description=msi%20660%20ti&bop=And&CompareItemList=-1|14-127-696^14-127-696-TS%2C14-127-697^14-127-697-TS
Here's how the 660 Ti PE stacks up versus other cards on a "cost per frame" basis
Guru3D uses the following games in their test suite: Hard Reset, COD-MW2, Far Cry 2, ANNO 1404, Metro 2033, ANNO 2070, BFBC2, BF3, Crysis 2, AvP, Lost Planet 2. Total fps (summing fps in each game @ 1920 x 1200) are tabulated below along with their cost in dollars per frame @ 1920 x 1200:
660 PE gets 851 fps for $300 at a cost of $0.35 per frame
7870 gets 701 fps for $280 at a cost of $0.40 per frame
670 DCII gets 999 fps for $420 at a cost of $0.42 per frame
670 gets 917 fps for $400 at a cost of $0.44 per frame
7950 gets 746 fps for $330 at a cost of $0.44 per frame
7970 DCII gets 924 fps for $415 at a cost of $0.45 per frame
680 DCII gets 1077 fps for $520 at a cost of $0.48 per frame
7970 gets 872 fps for $420 at a cost of $0.48 per frame
7970 GHz gets 952 fps for $470 at a cost of $0.49 per frame
680 gets 989 fps for $500 at a cost of $0.51 per frame