Wow your PSU is such an overkill, the DDR3 version and the DDR5 version are roughly the same, the 6570 uses barely enough memory bandwidth to benefit from DDR5, it's more of a throw-in-DDR5-so-people-will-buy thing.
I can hardly recommend you that card, with GTS450s readily available for $80 after rebate, and you have a good PSU to power it, it seems non-sensical to spend $60 on these cards.
As for the fan noise, your case has fans.
Did I mention your PSU is too good?
Uhm, just ignore the PSU. it's just a spare I had lying around.
According to that review I linked the GTS450 doesn't fair as well as the GDDR5 6570 and 6670 in the HQV test. Which is the most important thing for me as I only play older games on the machine. I'm a little bit finicky about fan noise I really don't want to hear anymore noise. Personally the noise I hear from my case fans right now is too much for me and it's really not loud. So adding another fan might just bug me.