"It is going on two years since support for Scalable Link
Interface (SLI) was introduced into NVIDIA's Linux binary display
driver. This support had come a year after it was officially
launched and supported by the Windows ForceWare display driver. As
we had seen at the end of 2005 with two GeForce 6 graphics cards in
SLI, its performance was very sluggish, and there were a number of
problems to be found with Linux SLI. While we have routinely tested
new NVIDIA graphics cards under Linux SLI internally, there hasn't
been much to report on as the experience has been very foul.
However, things have changed recently and with the recent NVIDIA
100.14.19 display driver release using GeForce 8 hardware -- we
finally have some modest numbers to report on in a Linux SLI
configuration. Linux SLI is still far from perfect, but in this
article we've used two GeForce 8600GT graphics cards in an SLI
configuration under both Linux and Windows to compare the single
and dual GPU performance under both operating systems..."