I'm currently considering upgrading my graphicscard from an AMD HD5870 1GB to a nVidia GTX 580 1,5GB.Can anyone please comment on expected fps performance and visual quality improvements?Thanks for your help.

They both have 58 :) both are good. For fsx nvidia is termed better.

Should see a pretty good improvement : http://www.anandtech.com/bench/Product/294?vs=305

You're going to see zero improvement. Both are top notch cards. You're not going to gain anything by going for a better card because there's nothing to increase. After a GTX570 level, nothing except the ability to run higher AA and maybe 1 or 2 frames here or there in heavy autogen will come. Not worth the $150 difference between the 2 cards. The only way to make a notable change in performance in FSX is to upgrade/overclock the CPU

Thanks for your feedback. Guess I'll pass on the GTX580 for now and save up a bit more to get myself a fine SSD.Processor upgrade will not happen before release of the Intel Ivybridge.

I think the 570 is a great card. It offers that little bit of extra headroom over the 1GB marks and is very quick. You would see an advantage over the ATI in clouds, ATI cards are very renowned for their prformance in clouds, not good.

Hey fwerff, I am using a 580 but was using an AMD 6970. Do you have any issues with 3rd party airports shimmering or sort of a moire effect going on? Or maybe just far off distant scenery having that issue? If so, that is where the 580 would probably improve if you tweak it with Nvidia Inspector. I'm always curious how other AMD Radion owners currently rate their experience. I like actually the AMD cards better but FSX is the only reason I use the 580.