Nvidia gt 640 vs gtx 650 vs gtx 650 ti

[hypershadow5g]

I know the obvious choice might be "650 ti", but I'm looking for a low cost, low power, low profile, cool running physix card.

I have a gtx 560 ti, and for physx (I like BL2), I'm using a gt 520, and that thing sucks beyond comparison. I had a normal 560 running physx before, but I'm only running a 600w psu with only 2 native pci-e connectors, so I didn't want to run adapters for the pci-e power anymore, nor did I want to put that much of a load on my psu. I've done my research, and the specs of each card (that I care about) are:

640(oem): gddr5, kepler, no pci-e power connector, 75w TDP (essentially an underclocked 650)

650: gddr5, 1 pci-e 6 pin power connector, 64w TDP

650 ti: gddr5, 1 pci-e 6 pin power connector, 110w TDP

So, I want the lowest wattage with good Physx performance. The Ti has 2x the cuda cores as the 650, but also almost 2x the TDP (captain obvious alert). The 640 somehow uses 75w instead of 64, even though it has lower clocks. Here's what I want to know: With the low TDP of the 650, is it really going to be using much of the 12v rail, or do you think nvidia just put the connector there to make sure the card had its own dedicated rail without relying on the pci-e slot?

Also, why on earth would the 640 use 75w??

 

[hypershadow5g]

And as another note, I don't want a gt 640 ddr3, because I've read reviews that have said the ddr3 interface on modern cards creates a bottleneck and actually hinders performance, so anything with ddr3 is out

 

[Cons29]

will these combination (gpu+physx ) be better than a single card? say a 660ti? just wondering, not sure how much the cost differs

 

[hypershadow5g]

Well when I was running the 560ti + 560 (physx) set up, I saw a boost in fps when playing BL2 with physx on. When I was just using the 560 or the 560ti, I either had to turn physx off, or I got lower framerates. I'm assuming (just assuming, though) that it would be the same with a 660ti. Also, anything more expensive than a 650 ti is out of my price range, which is why I want to keep the 560ti and just add a physx card. A cheaper way to bump up my fps a little bit.

 

[Cons29]

how about selling your gpu to add to your fund? lower temp and power consumption probably?

 

[drkrazyrich]

just checked online gtx 650 vs gtx 560 ti and the 560 ti kicks ass at over 55% better performance ,now according to the website 650ti has 12% memory band width and 95% texel rate but 20% less pixel rate
and 20 watts less power for the 650 ti and the gtx 650 uses 64 watts vs 170watts for 560 ti (hwcompare.com) so 560ti beats plain 650 but not the 650 ti .