excellent post regarding XP10

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Keith Smith
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excellent post regarding XP10

Post by Keith Smith »

Andy Goldstein has been involved in the XP community for as long as I can remember (and I've been using it since V4). Someone asked about buying a new PC for XP10 and listed a bunch of details of the upcoming hardware purchase. Andy made an excellent post that I thought was worthy of posting here. Of news to me was the new use of an OpenGL technique called 'instantiation' which is going to greatly increase the performance of rendering objects. This may well mean that Xp10 will be faster than XP9 on a given piece of metal.

This also confirms my thinking that gobs of memory doesn't do much for you (X-Plane's limit is 3GB) and that gobs of cores won't do much for you.

Here's the post:
Obviously we won't know X-Plane 10's performance characteristics until it's out, and even then they will change over time. I can offer a number of observations, though.

(1) Don't get too carried away with the multi-core thing. Austin's announcement a couple months ago was only that the flight models of other aircraft would be multi-threaded. The whole graphics engine is still single-threaded and will continue to be until the operating systems implement multi-threaded OpenGL. I don't know if that's even practical. The graphics are still the lion's share of the cpu load, so unless you're planning on flying with 100 other aircraft in the air, a quad core cpu will be more than adequate. Opt for faster cores over more cores. Faster RAM and bus is also a good thing.

(2) RAM: X-Plane 10.0 will still be a 32 bit app, so it will be limited to using 3GB of RAM. The other 3 is good for the OS and whatever else you're running. Personally, I predict there will be a 64-bit version of X-Plane sometime in the V10 run - we are already seeing address space pressure from large photo-real scenery. 6GB is good for now, but you'll need a memory upgrade a year or two down the road. My MB takes RAM in pairs, and I opted for 8GB instead of 4. Fortunately RAM is cheap.

(3) HD: 10K rpm is a waste of power and money, IMO. HD speed only matters for startup and loading scenery. Scenery is loaded in the background, and as long as you stay below Mach 100, HD bandwidth is not an issue. (Seriously, I ran the numbers a while back and the average data rate for loading scenery is low enough you could get it off an optical drive. Not a floppy, though.)

(4) Video card is a big question mark. V10 has a huge boost in object performance from an OpenGL feature called instantiation. It boils down to loading an object once into the video card and then plunking down multiple copies all over. This is a huge win for the default scenery, and any package that uses replicated objects. There's no benefit if all your objects are different. Ben has been testing with high end ATI cards, and object performance with instantiation screams. He has no data on nVidia yet. (Doesn't mean nVidia is bad - he just doesn't have any data yet.)

On the other hand, I expect Ben's advice against SLI will continue to stand. Because of the way X-Plane does multiple rendering passes, and uses rendering results as textures for subsequent renders, SLI (or ATI's Crossfire) might actually make performance worse. Don't spend any money on SLI until you've seen some documented and reproducible results. ("Very dangerous, Indy. You go first.")

High end video cards are ridiculously powerful. I have a GTX 460 that cost me $160 (if the vendor coughs up on the rebate) - good but hardly top end. It runs a full HD display with lots of the gpu intensive features turned on without breaking a sweat. VRAM requirements are all about textures - frame buffer space for the rendered display is miniscule. With the UK photo scenery at extreme res, I'm using not quite 1GB of VRAM, as shown by X-Plane's Rendering Options menu.

(5) Network "accelerator"? Irrelevant. An old 10 Mbit ethernet is more than adequate for all of X-Plane's networking.

(6) Win 64 Home Premium: definitely. But the higher tiers of Win 7 have nothing that matters to X-Plane.
Daddy O
Posts: 450
Joined: Mon Nov 08, 2010 9:32 am

Re: excellent post regarding XP10

Post by Daddy O »

This is good news. I have 3 PCs to upgrade (soon to be 4) if XP10 needed upgrades. My current hardware should be sufficient. Now I only have to find money for 4 copies of XP10 :(
Brian Ratledge
Posts: 76
Joined: Thu Oct 07, 2010 6:50 am

Re: excellent post regarding XP10

Post by Brian Ratledge »

Excellent news for sure.
Brian Ratledge
Pilot Client Support Team
brian (at) pilotedge (dot) net
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