I have read at http://www.jetlinesystems.com/performance.html that "SLI Impact on FSX(multiple graphics card configurations)Our testing has proved that SLI graphics will only improve performance when run on extremely high display resolutions. Although many games benefit from SLI, FSX typically will not."Also, I have read here at avsim people posting things like compared to a single 2gb card they get faster results in SLI with two 1gb cards.Does anybody know the truth about SLI and is it a benifit too either fs9 ,FSX or not ?

The "real truth" is that SLI/Crossfire do not improve FSX performance except when running absurdly high resolutions and amounts of AA. FSX's code is not written in a manner which can be accelerated directly by multiple GPU rendering techniques (i.e. SLI/Crossfire). As for Jetline Systems, they're a vendor trying to sell a product. The more expensive the product they sell, the more money they make. I'd take anything they say about FSX with a grain of salt.

It's true because FSX is a CPU limited app - by definition there's nothing for additional GPUs to do aside from on-chip features like really high AA levels.

ummm.... is it just me or is Jetline Systems agreeing with your statements on SLI performance? From what I have read on their performance link, they DO NOT recommend SLI for FSX. SLI Impact on FSX(multiple graphics card configurations)Our testing has proved that SLI graphics will only improve performance when run on extremely high display resolutions. Although many games benefit from SLI, FSX typically will not. A single GPU (single card) solution is recommended.