PCI-E 2.0 x16 card on v1.1

You should have no problems at all.

Only PCI-e 2.1 cards (and maybe PCI-e 3.0 cards) might have compatibility issues with older PCI-e 1.0/1.1 slots.

The GTX 550 Ti is too slow to max out PCI-e 1.1 bandwidth.

And for this card exist an additional pin connector in corner ,for power. But do i need put that cable or if only installing SLI ? With other words, what criteria should i look?

The card requires the extra 6-Pin power connection. Do not attempt to power up your system without the extra power connection from your Power Supply.

-Wolf sends

@Wolfshadw

Hey wolf, if you have some secs to spare, please check youtube(dot)com/watch?v=BaTpiFh8Ivg and as you see from 3:08

that guy clearly tells he not recommend using the extra cable. He instead suggest updating PSU , so if I'm going to buy this card+OCZ ModX of 500W might be ok considering the recommend of that guy ?

If your current power supply does not have the 6-Pin PCI-E power cable, then it's probably a good idea to go ahead and upgrade the power supply. I tend to stick with power supplies from Antec or Corsair, so I can't give you any advice about the OCZ. It does have plenty of good reviews on Newegg. However, if this is going into an older system, then make sure it has all the older power leads you need as well as the newer ones for your graphics card.

-Wolf sends

Yeah cuz OEM was so bastards to put in this PC a 250W psu -.-'... so, i'm stick to that 500W OCZ for 50 bucks, i think is good solution , have also 82% efficiency ..