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Question for Umberto about GPU RAM and 64bit O/S
virtuali:
--- Quote ---So, what is the correct answer since we have two conflicting answers? I'm building a new sytem that will be on a 64bit OS and most of the choices in GPU now are 2GB and higher, but dont want to buy one that is going to cause problems if Pauls answer is correct.
--- End quote ---
Yes, that's another thing to take into account, which is DX9 vs DX10, this is the official explanation from Microsoft:
http://support.microsoft.com/kb/940105
With a GPU with lots of VRAM, it's probably best to use DX10, if possible. Of course, 64 bit OS still has an advantage, because on a 32 bit OS, everything that is running a a certain time (including the OS itself) will be taken from the same overall shared pool of 4GB.
Paul J:
If you want to try DX10, Sean - here's a "How-To" doc - https://dl.dropbox.com/u/52676345/DX10_Fix/Notes/DX10%20Notes.doc with links to other resources within. ;)
cmpbllsjc:
Thanks guys.
So it's probably safe to go with a 2GB GPU on a 64bit system for FSX, but nothing more than that? I will still probably run in DX9 mode so that I dont have any compatibility issues with 3rd part addon ons. Although since I have been on XP forever and will finally be switching to an OS that is capable of trying the DX10 preview, I will probably give it a shot just to see what it looks like and how it performs.
Now that I think about it, I remember seeing a tweak mentioned in the PMDG forum that was a line you could enter in the FSX.cfg that would prevent a GPU from using more than X amount of its on board RAM. I'll have to take a look to see if I can find it.
altstiff:
--- Quote from: Paul J on November 15, 2012, 06:49:36 pm ---
--- Quote from: altstiff on November 04, 2012, 09:22:54 am ---I know that on a 32bit O/S the GPU's RAM is mapped through the Virtual Address Space. On a 64bit O/S is the GPU's ram mapped the same way?
The reason I ask is that since I have upgraded to a 3GB GPU I have seen more OOM errors than before (with a 2GB GPU).
Thanks in advance
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Hi Al; Yes - it's mapped that way - but your problem is likely due to the way DX9 manages graphics memory. DX9 creates a 2-gig reservation in the system memory - at least the memory is reserved - whether it's used or not. Going to a 3-gig card made the situation harder to avoid. By comparison - DX10 doesn't do this - so very few, or even zero OOM's for that reason. It's one of the reasons FSX, using DX10 is far smoother, and allows for better graphics. If you want to test this out - grab Steve's patch herehttps://dl.dropbox.com/u/52676345/DX10_Fix/shader_release_v3.1.1.zip and browse through the "How-To" doc here: https://dl.dropbox.com/u/52676345/DX10_Fix/Notes/DX10%20Notes.doc
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Thks for this Paul. Explains why I was getting OOM issues when I never got them before.
Paul J:
A 2-gig gpu should be plenty, Sean: With less than that I have no trouble in maintaining a very solid and smooth 29.9 - 30.0 fps in the heaviest areas. My DX10 tests are usually done into the downtown core of Jon Patch's Vancouver+, with "Building Storms" or "Fair Weather", about 20/20/20 traffic with 1 airport vehicles: hundreds of circuits. I've dumped the photos now, but they were all about two - three seconds apart, and all were consistent at that frame rate. GTX 580 - 1.5 gig, not o/c'd, and a 4.9 gig 2600K, o/c in the bios. Memory is important - the best timing possible and 1T.
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