Help/advice/assistance with crossfiring (GTX560ti, GTX 550ti)

[mrdoctorsir]

Hello, it was only recently that I built my current PC, currently I'm running a solo GTX560ti, and I have never cross fired GPUs before.
I have available to me an excellent deal on a GTX 550ti, would there be a worthwhile, and noticeable, performance difference with the 550 as an added card? (The 550 itself would run about $130, not including power supply cost (please suggest))
Also, I know I would definitely need to improve my power supply. (specs below) Can anyone advise me as to what wattage I'd need to run the second card?

CURRENT SPECS:
CPU🙁Intel i7 2600k) GPU🙁GTX560ti) MB🙁ASUS Maximus IV) RAM🙁2*4gig Ripjaw) DRIVES🙁one: Crucial M4 64gig and one: Samsung Spinpoint (1terabyte))
Current power supply is a 620Watt Seasonic.

Also, does anyone see any bottle-necking/underlying issues? ...Still kinda new to this... Thank you for any, and all advice.

 

[FtsArTek]

For a start, SLI is for nVidia cards, and unlike AMD cards, you need to have two cards with exactly the same card.... You would need another GTX560Ti, a 550 wouldn't work with that. I can't see any bottleneck, no issues... You'll want a 750w Corsair or similar

 

[refillable]

No, If you want to crossfire 560 ti, make sure you get the same 560 ti also.

 

[k1114]

Crossfire is amd, sli is nvidia, they are different things which is why cf can work in 4x and with different cards while sli requires at least 8x and the same card. The speeds can be different, the faster card will downclock though. And brand doesn't matter either, as long as its the 560ti 384cuda version.

 

[JackNaylorPE]

You could use the 550 as a Physx card but not in SLI.....that would require another 560 Ti

http://www.geforce.com/Hardware/GPUs/geforce-gtx-560ti/specifications

Thermal and Power Specs:
Maximum GPU Temperature (in C) 99 C
Maximum Graphics Card Power (W) 170 W
Minimum System Power Requirement (W) 500 W
Supplementary Power Connectors Two 6-pin

So ..... 500 + 170 minimum for two ..... I'd use an 850 if OC'ing the CPU and GPU's