I suggest you check the length before buying (might vary between manufacturers). Below are reference design specs:
GeForce GTS 450, 106 W TDP
GeForce GTX 460 SE, 150W TDP – Avoid this card; lower clocks but just as power hungry!
GeForce GTX 460, 768 MB, 150W TDP
GeForce GTX 460, 1024MB/2048MB, 160 W TDP

Again check the card details before buying (there are many OC’d versions of both the GTS450 and GTX460 so the actual power might vary substantially from reference designs).

If you must buy now then it's between the GeForce GTS 450, 106 W TDP and the GeForce GTX 460, 768 MB, 150W TDP. Don't even consider a GeForce GT430.

The GTX560 and GTS550 are expected in the first quarter of 2011, but while they could arrive in Jan my guess is that it's more likely to be Feb or March. I would expect better performance from both (between 10% and 30%) and for both to use slightly less power (perhaps reference will be around 95W and 130W, but the manufacturers will no doubt come out with a large variety).

In Germany I see the GTS450 for 100€ and the GTX460 768 MB for 130€. The GTX should be about 65% faster (assuming 700 and 800 MHz for GTX and GTS, respectively). The GTX is certainly more power efficient and price efficient.

Yet the GTS is still cheaper and much less power hungry. Personally I'd probably go for the GTX - if I invest 100€ for a GPU I could as well add another 30€. If I can't then I probably shouldn't be spending the 100€ either. The GTS450 wouldn'T be a terrible choice, though, given your power contraints.

Checking actual card length is certainly important. And I'd also look for a solid cooling system which exhausts as much heat as possible. You might also be interested in getting a card where you can control the voltage via software. By lowering voltage (and maybe clocks as well) you can run more power efficient and cut another 10 - 30 W from the power consumption.

MrS
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Scanning for our furry friends since Jan 2002