3GB Switch - interesting side effect

[Cruachan 705]

Hi,In certain situations in FSX I have noted occasional graphic spiking - black vertical lines which come and go very quickly. It's not a major issue for me but I thought I would experiment with the use of the /3GB/Userva=xxxx switch in the system boot.ini file.So far I have not seen much change when using various values for xxxx and I have tried various values from 2560 down to 2432.I have 2GB of physical ram (DDR2) and the paging file size is fixed at 3072MB.My graphics card is a NVIDIA GeForce 8800 GTS 640MB (DDR3) (ForceWare 182.08 WHQL)Now, the interesting side effect:I have been using Raxco's Perfect Disk for many years. It has proved to be 100% reliable and I am currently on version 10 Pro.I have XP Home on a 20GB partition on my main drive (yes, yes, I know, I can see all you frowning pundits (lol), but this configuration suits my purposes very well. I don't see any significant drive-related file access performance issues and drive activity is usually minimal during FSX flights). FSX, FS9, Falcon4, Lock On, RealFlight G3.5, Oblivion, The Half-Life 2 series, X2-The Threat, X3-Reunion, Orbiter, Celestia, Space Shuttle Mission 2007, etc, etc, etc (you get the idea) are all installed on my D: partition and all run just fine.Anyway, I thought it was time to defrag my 20GB system partition so I did the usual SMARTPlacement defrag followed by the offline boot-time defrag of the system files. During the latter operation I noted a message stating there was insufficient memory to defrag the paging file. This seemed strange (>6.5GB free on the partition) so I tried the effect of reducing the values set for Userva=xxxx from 2560 in decrements of 64 down to 2432 but still no change. I then tried deleting and then resizing the paging file to 2050MB but this also had no effect, In fact this message persisted until I removed the switch and, once again, all was well and Perfect Disk completed the operation without any issues.I hope Nick or someone can explain why this has happened and what effect the /3GB/Userva=xxxx switch is having on memory available to PerfectDisk in offline boot-time defrag mode.I've now reconfigured my boot.ini file meantime with an additional line that allows me now to boot with or without the switch. That way I can continue experimenting until I can decide one way or 'tother whether to keep the /3GB switch option:[boot loader]timeout=10default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS[operating systems]multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Normal Startup" /fastdetect /usepmtimer /NoExecute=OptOutmulti(0)disk(0)rdisk(0)partition(1)\WINDOWS="More Memory Startup" /fastdetect /usepmtimer /3GB/Userva=2432 /NoExecute=OptOutC:\CMDCONS\BOOTSECT.DAT="Microsoft Windows Recovery Console" /cmdconsNot a critical finding, but interesting nonetheless.Mike

[Daveo 36]

Why would you use the 3GB switch with 2GB's of ram in the first place?

[FlyingsCool 3]

Why would you use the 3GB switch with 2GB's of ram in the first place?

I'm not going to get this totally right, but, the 3GB switch relates to the use of total "virtual" memory, it doesn't have anything to do, directly anyway, with your physical memory.

[Cruachan 705]

I'm not going to get this totally right, but, the 3GB switch relates to the use of total "virtual" memory, it doesn't have anything to do, directly anyway, with your physical memory.

Yes, that's my understanding as well.I was following Nick's helpful advice in his now renowned posting over at the SimForums:http://www.simforums.com/forums/forum_posts.asp?TID=29041Mike

[n4gix 4,947]

Why would you use the 3GB switch with 2GB's of ram in the first place?

Because that switch has absolutely nothing whatever to do with memory at all. It has everything to do with the Virtual Address Space table.It matters not whether you have 512MB of RAM of 4GB of RAM...The reason the OP's program complained is because isn't marked as /LARGEADDRESSAWARE so could not take advantage of the increase in VAS...In fact, because of the presence of the switch, the program thought it didn't have enough VAS allocation...The OP took the correct action by providing a dual-boot option.

[Cruachan 705]

Hi n4gix,Thanks for the info. Now I understand."The OP took the correct action by providing a dual-boot option."Hey, nice to know I did something right for once ...lolRegards,Mike

[OldMaintChief 7]

I have the spiking in DX9. I don't use DX10 because addon planes have white skins. When more are coded for DX10 maybe I will turn it on as I get better looking aircraft and higher FPS. My computer came with 2GB 1066 memory. I first got the spiking when I upgraded the 169.25 driver with the next version. When I rolled back the driver it went away. Nothing else was changed. I installed 2 more sticks of the same type memory and the /3GB switch in both XP and Vista. Same indications. Installed the next, next driver and got the spiking. Rolled back to 169.25 and it went away. I tried several tweaks per PhilT and NickN with no help. In my case, I am sure it is the driver. Lead Pursuit said the problem was in the new drivers and they could issue a patch to work around the problem. though they didn't explain the issue.Have FunDaveSystem:Dell XPS 720 H2CIntel Quad Core Extreme QX6800 @ 3.73GHz4GB (2x2GB) Corsair Dominator EPP 8500C5D FSB 800MHz @ 1066MHz2x160GB WD SATA Raptors, Sound Blaster X-FiNvidia 2x8800GTX 768MB SLI, Dell 2407WFP PanelXP driver: 169.21, Vista driver: 169.25Logitech Z680 5.1 Speakers, G5 Mouse, Saitek X52WinXP Media Edition SP3 on C: (SATA 0) w/ Internet/AV/Office/FS9/Falcon4 AFVista SP1 on D: (SATA 1) (Dual Boot) w/FSX3DMark06: 17,018/6992/7123/5667