Windows 7: Precisely what cards support SLI feature

This is proably a very common question but could not find a clear answer after searching here and googling for 3 hours, so...
Precisely what ACTUALLY does a SLI configuration require? I keep seeing these lists of "officially supported" video cards and noticed all of them are ones who have goldfinger connectors but i know for a fact these are not mandatory for SLI. I know, or at least thought i knew, 2 identical (or same chipset) cards are required and a capable motherboard. Now all sorts of people claim that ONLY the stated cards will be able to SLI and i don't understand why. It's clear as of drivers 3xx it's not possible to use cards with different amount of memory any longer but other than that there's no other stated restriction.
Background story: one of my 9800GT's has gone to hell and could not find another one whatsoever so i sold the other one. I had laying around a GT520 way inferior card but newer technology and want to keep it since newer games refuse to run without DirectX 11 hardware support, another reason i sold the remaining 9800. I am about to receive in 2 days another identical GT520 and i can't get a definitive answer as to whether they will actually be recognised as SLI-able or not.
They have no goldfinger connector and "officially" are not supported but for low end cards like these that use very little PCIE bandwidth should not be a communication problem, provided the drivers agree to work for me not against me as they have with the 9800GT's in the past. (i always had to use the coolbits registry tweak even with bridge and identical 9800 cards installed)

No, the GT520 does not support SLI mate

Thanks for the info! Now that it's coming anyway i guess i'll just check just in case it works... a single one is weak in gaming but two would be decent or so i hope. If not... selling again.
And i'll post the results here, maybe it would help some people/

yeah, unfortunately you're out of luck in this case.

Here you go: Supported GPUs | GeForce

Thanks! A little while ago i found out why that list is strict... in later drivers they removed support for bridgeless SLI... just because they can. So if that proves to be true it's goodbye Nvidia, AMD from now on.

You`ll be making a mistake, in my opinion

And in mine.

I agree Nvidia is way ahead as far as performance and driver quality, but i find this "we do whatever we want if you don't like it stop buying" unacceptable. Looks like these days both software developers and hardware manufacturers are taking the "forced upgrading" really serious because apparently the planned lifespan of the average video card is not quite as predicted so sales would drop like a rock once everyone has decent cards.
As i said, if there is no more SLI option, then i'll have to rethink the graphic card scheme or the whole motherboard/cpu/ram/video since it will have become pointless to use a SLI motherboard that other than SLI offers nothing, on the contrary is quite old technology already (it tops at DDR2 800Mhz and FSB 1066).

With today`s cards, you don`t even need to go sli, but that`s an argument for another day