Nvidia has announced limited sli capability between the GTS250 and the 9800GTX+. There are a few requirements though, they need to be the same memory size and memory speed of 2200MHz. If the memory is 2000MHz the card will not work, and OCing the memory of the GTX+ will not work either, this is a bios limitation. It will SLI with the dual 6pin version of the card however you will need a flexible bridge. You can also do 3way with 2 9800GTX+ and a GTS250 or a 9800GTX+ and GTS250 however they would all need to be the single 6 pin version of the card since the SLI connectors would not line up.
SLI will not work with the standard edition 9800GTX, only with the +.
We also recommend to use a flexible SLI bridge, as the alignment of the SLI pins on the two different cards may be offset from each other.
CM Cosmos II Ultra/ EVGA 750 G2/ Z87 Classy/ i7 4790K/ 8gb 2400mhz/ GTX 1080 SC/ Upstar 28" 4K/ Windows 10 64
