... I think FSX has absolutely ridiculous requirements ...
Well, this is one of the funny parts. You see my config below. Nothing overclocked, everything standard. Win7-64 bit. Running AES on the same machine. I can even run the Concorde at London Heathrow MegaAirport with 25 FPS (locked). It is an open secret that it does not just need the most powerful components to run FSX but it needs the componentes that match each other. My supplier has a quite good hand for that
The amount of "needs" of FSX are directly proportional to what the user's preferences are and what amount of hardware or optimization needed to achieve that. Your machine could easily be humbled, its just a matter of adding in "stuff" or perhaps moving your sliders until it saturates your processor and graphics card. You choose to have MegaAirport Heathrow, I have chosen other things.
There is nothing wrong with my machine or my ability to optimize it for FSX. I built it after extensive online consultations with somebody known as an FSX guru. What do you think of this processor? What will my bottlenecks be? What is the fastest RAM to match my processor? How do I configure my AHCI ports? What drivers should I use, how do I optimize this, and that, and the other thing...All these questions were worked out beforehand. I'm reasonably sure my machine and its optimizations, both hardware and software are as good as anybody's out there.
I don't know what other addons you are running, but I insist on some heavy 3rd party Airline Traffic, Heavy Autogen, large radius LOD, UTX, REX, GEX, FEX, FS Global Mesh, Track IR, etc...My sim is loaded to the gills, and my sliders are pretty far to the right. In fact, my settings are Optimized around the Concorde. I am running the maximum amount of addons and sliders that I can that allows me to depart default LHR in the Concorde during a thunderstorm, and at dusk which will allow me to get 18 FPS. I suppose if I insisted on running Mega Airport, I could adjust accordingly, but certain other things would have to suffer. I have an absolute insistence to run the same IQ settings for the Airliners as I do for flying VFR in a Cessna. I want the visuals on my takeoffs, landings, and low altitude flying to be absolutely consistent no matter what I'm flying, so I don't make any sacrifices to Autogen or Scenery complexity just because I'm going to be flying at 50,000 feet. For the record, I consider Concorde X to be a lot more frame friendly than the PMDG 747, but a little less frame friendly than the MD-11. My only A2A product, the Stratocruiser, is somewhat less resource intensive than any of the aforementioned.
Or let me guess, you are one of those guys that has all sliders maxxed, 100 % Cars, and 100% Third party Airline Traffic, and run twice as Mesh, Landclass, and Scenery addons as me
(I'm just being a wiseass, but I've been a part of many discussions like these
Whenever I hear somebody tell me they are getting X amount of FPS at MegaAirport Heathrow in the Concorde (and you aren't the first), all I can say is that it is a matter of deciding what one's priorities are in terms of image quality settings. The machine to conquer FSX hasn't been built yet, and I guarantee if you add more scenery addons or other things in, move your sliders farther, etc, you will be able to bring your rig to its knees, and no amount of skillful optimization will do. I know that you know that already.
P>S For the sake of full disclosure I have never tried to run Megaairport Heathrow on my rig in its current configuration. I recently re-built my machine with a new processor, ssds, and new graphics cards, and Uber fast RAM. Previously I was running a I920 overclocked to 3.9 ghz, with GTX 285s, and an older hard drive, and I didn't have the Concorde X then, although I was still running at a resolution of 4320 x 900 off of a Matrox just like I am now. I can tell you that the PMDG 747 was not satisfactory at Megaairport. Only the Aerosoft Cheyenne had decent framerates there. I doubt it would be much better with the i980 or the GTX 470s, so I never reinstalled it.
I recently bought Aerosoft Tahiti, and I'm eager to fly the Stratocruiser there from Hawaii. An initial check out of my frame rates at Tahiti X were very positive, but I doubt that can be used as a benchmark for how Heathrow would compare.