Despite what all the self appointed experts will tell you, FSX can and will make use of a second GPU to increase performance. The caveat however is that it will only do so for a specific type of setup, and in certain sim conditions. Anyone running huge resolutions, and/or massive levels of AA will see a benefit from a second card in a high GPU stress area of FSX (think thunderstorms at altitude, where the cpu isn't bound). There's a couple of threads kicking about where people who have actually bothered to test and prove this, and in fact even Phil Taylor himself has confirmed this in his blog (anybody going to question him?). Granted, it's not really much use for the majority, but it just riles me a little when people spread what is ultimately misinformation as absolute fact. There's so much of that around here, and I often see it waste many peoples time.

Hmm this got me thinking again, now here's what I did I first ran FSX in normal mode I got 14.7 fps @1280x768 and then I used ATI Cfx xtension same location same settings same aircraft (Baron 58) I got 17.1 fps. Now I am confused what does it mean ? Both are ATI cards one is on board and the other one is a HD 5450 and under GPU-Z both card sensors run full in fsx. I repeat again both these cards are incompatible to each other for crossfire. Any one ? Or should I check again ? damn this is confusing.

Despite what all the self appointed experts will tell you, FSX can and will make use of a second GPU to increase performance. The caveat however is that it will only do so for a specific type of setup, and in certain sim conditions. Anyone running huge resolutions, and/or massive levels of AA will see a benefit from a second card in a high GPU stress area of FSX (think thunderstorms at altitude, where the cpu isn't bound). There's a couple of threads kicking about where people who have actually bothered to test and prove this, and in fact even Phil Taylor himself has confirmed this in his blog (anybody going to question him?). Granted, it's not really much use for the majority, but it just riles me a little when people spread what is ultimately misinformation as absolute fact. There's so much of that around here, and I often see it waste many peoples time.

Di, you are speaking about something you know nothing about....The OP queried the use of two or more graphics cards, and no one said anything about SLI or Crossfire. I have three separate video cards in myP5E64 motherboard and none of them are configured as SLI or crossfire, in fact they are three different cards. Andrew Vincent

Sorry. Let me go trot down to newegg and pick myself up a second GTX580 on the fact that I MIGHT see 1 or 2 frames more in a certain and specific situation

Don't be facetious, that's not the point. And for the record, those who have done this have seen far more than a 2fps improvement.

Sorry. Let me go trot down to newegg and pick myself up a second GTX580 on the fact that I MIGHT see 1 or 2 frames more in a certain and specific situation

Wow, that was a helpful and informative comment. You were pontificating and got called out. Again. Did you really think sarcasm would help? How geekish.

Actually having a GTX 590 with 3 gigs of ram will slow down everything in FSX. FSX IS a 32 bit program and mostly uses CPU for it's graphics performane.Having a graphics card with more than 1 gig is starving FSX of memory. I think this is one of the reasons that people with very high spec machines are having the most problems with the NGX.

Have a look at the site link below...These guys build machines for Flight Sim use. I used the performance guide they have, as reference to build my current system and I have had very good luck with performance in FSX. They say that multi-GPU use is only effective if you are running very high display resolutions, like three monitors. http://www.jetlinesystems.com/performance.php

Look who was right. That's a FSX system building company + 2 members agreeing that 2 cards are detrimental unless using ultra high resolutions + multiple monitors. Lets also remember that all the Vram comes off of your VAS, so more VRam means more chance of OOM's

Look who was right. That's a FSX system building company + 2 members agreeing that 2 cards are detrimental unless using ultra high resolutions + multiple monitors. Lets also remember that all the Vram comes off of your VAS, so more VRam means more chance of OOM's

Who said otherwise?

do the ooms with high vram also happens on a 64bit os ? or only on 32bit os ?

Look who was right. That's a FSX system building company + 2 members agreeing that 2 cards are detrimental unless using ultra high resolutions + multiple monitors. Lets also remember that all the Vram comes off of your VAS, so more VRam means more chance of OOM's

Look here smarty - you miss the point completely...why else would you have multiple cards if you didn't have multiple monitors, which we do...You need a lesson in manners. Andrew Vincent

Look here smarty - you miss the point completely...why else would you have multiple cards if you didn't have multiple monitors, which we do...You need a lesson in manners. Andrew Vincent

Actually the OP was asking about using multiple cards to increase performance. He never mentioned multiple monitors.

do the ooms with high vram also happens on a 64bit os ? or only on 32bit os ?

They happen on both. Because FSX is still a 32bit application. If it was a 64 bit application, then no, the chance of a OOM would be very unlikely, but because it is 32bit, it can only handle a certain amount of Ram, VAS etc

What we all really need is a single core 20GHz CPU with it's special cryogenic cooler. Intel must have told the FSX developers that they were going to make one.

What we all really need is a single core 20GHz CPU with it's special cryogenic cooler. Intel must have told the FSX developers that they were going to make one.

LOL you bet they did

What we all really need is a single core 20GHz CPU with it's special cryogenic cooler. Intel must have told the FSX developers that they were going to make one.

It took us roughly 6 years to reach the point we can max out, and we're still struggling to scrape up their mess :(That's terrible.