Out of Pod Experience

Pretty much as per above if you want to stay Nvidia - basically anything with the new Kepler cores. There's a lot of confusion with the NVidia models due to their rebadging exercises and anything older than the Keplers weren't really as competitive vs the new AMD Radeons 6000/7000 series.

Just had a cheap ATI 6670 DDR5 for replacement for on my aging C2D. Works like a charm except I can't control the fps intervals for EVE, so it's locked to v-sync. Ramped up the fan to work at 100% at all times and it stayed silent. I don't really trust the auto-fan management, got burned twice before, never again These newer 40nm cards runs damn cool (30-50C range). My brother had a chance to try out the ATI 7750 DDR5, these 28nm cores run just as cool and performance wise equivalent to the older NVidia 8800GT, if not slightly better.

Only reason why I swapped to Radeon (from years of using NVidia) was price/performance competitiveness. Would have liked to get the new Kepler cores, but they haven't completely replaced the lower-end market as yet. Oh one thing, I wasn't really keen on the Radeon drivers ... it's almost amateurish when you look at the interface. Seeing it for myself, I guess there might be some truth behind all that noise about Radeon drivers being sucky (especially for Linux boxes).

Since you are not buying top of the line card, get the cheapest one.

Both are about the same really, just comes down to price/availability

But I will say that the Asus cards with their custom DCU II heatsinks have to be the one quietest solutions I have ever heard if that's any concern to you. (I hate computer noise)

if your on a budget look at an i3/i5 solution.
Onboard Audio , LAN, 6-8 USB connectors are all good quality these days
Onboard Video for a desktop is the spawn of SATAN , treat a board with this like it has leprosy AND the "lurgy"

Find a local(ish) builder with a website that allows custom builds
Add/Remove parts (after checking compatabilty/tech specs) untill you make your budget work.
If thier site isnt displaying tech specs, find a better site.

Well, that's what I figured... I saw the 64 W thing and thought that it would not make much difference from 50 W. But I didn't tried to actually install the card and start the computer...

The new card does have a plug to plug it to the power supply, is it necessary? Or it' may be another "just in case" feature, like warning I'll need 500 watt?

The PCI-E slot itself can provide up to 75W of power, and additional power is provided via that plug (another 75W max through a 6-pin one for up to 150W total, because that's what you have on the card, I assume).
The power plug is there in case you want to overclock the card and thus drive your TDP from the stock 64W to above the 75W the socket can provide.

Personally, I would advise against overclocking.
It could even be possible to have your warranty voided in case you decide to ever overclock (and the card itself might even record whether if it was ever overclocked, but I'm not sure about that).

Rule of thumb approximation, for reasonable overclocks, power use generally goes up to the power of 3 compared to clock speed increase... so, say, a 10% hike in frequencies will generally require about 33% extra power, give or take. Environmental temperature and other things also play a factor, so actual results could vary quite significantly.
With just 75W-64W=11W -> ~17% extra wiggle room, you could at best hope for a ~5% overclock before you need additional power from the plug, and it would probably be recommended to plug that in even if you try just 3% overclocks, just in case.


Well, it's more about protecting themselves from the consumer's anger in a "worst reasonable case" scenario.
PSUs decay over time (the closer to their upper limit they operate, the sooner and faster they drop in performance), and cheaper PSUs generally slightly overstate their performance to begin with (if not worse), so it's not unreasonable to expect SOME non-negligible percentage of consumers to only be able to provide only about 60% of the power the PSU was originally rated at (or worse).
So, a cheap, quite old and frequently used near peak power 500W PSU turns into practically just a 300W PSU (or even less), and they don't know for sure what else you have in your machine (you might have an older and power-hungry CPU, you might have even overclocked it, and so on and so forth), so they figure if they tell you that you need a 500W PSU, that's enough for almost everybody to not have any insufficient-power-related issues until the video card warranty runs out.