Vista Memory Confusion

[Herbuk]

Hey all,

I recently took the plunge and upgraded my pc for a Vista one with better specs.

It should have 4Gb, and indeed, when the computer starts and the dos screen comes on with all those numbers and stuff it says there's 4gb RAM.

What's puzzling me is that the Dxdiag and System Info File don't show the correct amount of RAM. They say there's 2.3gb

So I rang the customer support people and they said Vista only tells you there's max 3Gb RAM then the graphics memory takes some as a buffer so Vista subtracts that form the 3Gb. Even though there is actually 4gb in there.

It sounds a bit strange to me, is this right or am I being fobbed off?

Thanks.

 

[TyroneShoelaces]

Sounds like you got the 32-bit version of Vista. You need the 64-bit version to support more than 3GB of RAM.

-TyShoe

 

[firemist]

Windows XP and Vista 32-bit can use up to 4GB. However, installed hardware will lock out part of the address range for things like the PCI I/O (the amount locked out will depend on what hardware is installed). Usually you get a little over 3GB of memory actually available for use in Windows.

Your reported value of 2.3GB of memory really seams low. What is in your system? I have 4GB insatlled and show 3.5GB available on my system.

 

[Hawkeye22]

Windows XP and Vista 32-bit can use up to 4GB. However, installed hardware will lock out part of the address range for things like the PCI I/O (the amount locked out will depend on what hardware is installed). Usually you get a little over 3GB of memory actually available for use in Windows.

Your reported value of 2.3GB of memory really seams low. What is in your system? I have 4GB insatlled and show 3.5GB available on my system.

http://support.microsoft.com/kb/929580

In addition, a Win32 process (under XP-32bit) can only access 2 gig of memory unless the /3gb switch is used in your boot.ini file. Not sure if this applies to Vista-32 also, but at the very least, you will need PAE turned on if it already isn't.

bcdedit /set pae ForceEnable

 

[fredgiblet]

How much video memory do you have? IIRC all the video memory must be shadowed meaning that if you have 4GB of RAM and 512MB of video memory then Windows will only see 3.5GB of RAM as available.

 

[zenmaster]

They are not yanking your chain.
I'm not too surprised with what you are seeing.

#1) Get a Video Card that does not use SYSTEM memory for video. Something like at 7600GT w/ 256 Meg of RAM would work well and run close to $100. This will help video performance quite a bit.

#2) You will likely need Vista-64 Bit to fully access your RAM. Some of the memory locations under 4gb need to be used by drivers and such and Vista is even more of a hog in this matter than XP was and hence what was a common 2.8gb-3.5gb limit in XP may be less in Vista.

From this limited number the memory from your graphics card is reduced.

It's issues like this why I recommend holding off till Vista SP1 when driver issues should be resolved and you can run Vista-64 w/o a problem.

I'm not bashing Vista, but it's a massive change from XP and likely a greater change than even going from NT4.0 in 1995 to XP in 2005 than it would be in going from XP in 2006 to Vista in 2007.

Its going to take vendors a while to make everything work.
It's amazing as much works as it does.

 

[Herbuk]

Thanks for the replies.

This is the spec from the dxdiag... (didn't want to post it all as it's really long)

------------------
System Information
------------------
Time of this report: 4/3/2007, 23:56:47
Machine name: MESHPC
Operating System: Windows Vista™ Home Premium (6.0, Build 6000) (6000.vista_rtm.061101-2205)
Language: English (Regional Setting: English)
System Manufacturer: NVIDIA
System Model: 122-CK-NF68
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel(R) Core(TM)2 Quad CPU @ 2.66GHz (4 CPUs), ~2.7GHz
Memory: 2302MB RAM
Page File: 625MB used, 4182MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 10
DX Setup Parameters: Not found
DxDiag Version: 6.00.6000.16386 32bit Unicode

The graphics is 2 x 768mb NVIDIA GeForce 8800 GTX in SLI
and the sound is Creative SB X-Fi


So am I stuck with 2.3gb for now? and the best advice would be to upgrade to 64-bit Vista after SP1?

Thanks again.

 

[Mondoman]

...
The graphics is 2 x 768mb NVIDIA GeForce 8800 GTX in SLI
...

So am I stuck with 2.3gb for now? and the best advice would be to upgrade to 64-bit Vista after SP1?....

Yes and yes.

 

[fredgiblet]

The graphics is 2 x 768mb NVIDIA GeForce 8800 GTX in SLI

Yeah this is what I'm talking about, IIRC that means you will at most see 2.5GB because 1.5GB of the address space goes to the video cards. the other .2GB I can't really account for, probably BIOS and other misc stuff. Best to switch to 64-bit when SP1 comes out if you can.

 

[Herbuk]

Well thanks for all the advice it's appreciated.

But it looks like I'm screwed as my Vista is OEM so I can't get the cheap upgrade option.

Anyone know when SP1 is supposed to come out?

 

[Mondoman]

..., IIRC that means you will at most see 2.5GB because 1.5GB of the address space goes to the video cards...

No, the video memory is not directly mapped into the main PC memory address space. The graphics cards do use up some memory space, but the setup is much more complicated than that.

 

[fredgiblet]

Anyone know when SP1 is supposed to come out?

I've heard rumors that M$ want to get it out in as little as 6 months, but I haven't heard any actual announced dates.

 

[underbyte18]

well I say go balls to the wall and get 16gb of ram. Thats just me though.

But it looks like I'm screwed as my Vista is OEM so I can't get the cheap upgrade option.

I actually know how to get a legal copy of vista premium upgrade for only $70.00. Wanna know? It's called a student discount. Booya!

 

[fredgiblet]

I actually know how to get a legal copy of vista premium upgrade for only $70.00. Wanna know? It's called a student discount. Booya!

I know how to get a legal version of the Business edition for free, you know how? Offer up my home computer to be a guinea pig for work, Booya!

 

[Herbuk]

Is it normal for the graphics cards to steal RAM? It didn't happen with XP Pro, DXDiag always reported back the full amount of RAM.

Shouldn't they be using their own memory?

 

[croc]

Your various devices under 32 bit will 'share' some of the 4GB RAM that you have installed. You are not being cheated, unless the memory that they are sharing is slower than your memory.

I'll not go into the long history of this, as a quick google search on your part would yield much faster (and possibly more accurate) responses than I can provide. (I type slowly!)

Here's a simple test that you can conduct though. Do something memory intensive... Say prime...

Pull two MB ram and repeat.

Then repeat the test, with a graphics memory test, say oblivion. Use fraps to measure.

my 2p....

 

[Mondoman]

Your various devices under 32 bit will 'share' some of the 4GB RAM that you have installed....

Not really -- they will use up some of the memory addresses that might otherwise have been used for physical RAM. See the recent Memory FAQ thread on this forum for a bit more info.

 

[Mondoman]

Is it normal for the graphics cards to steal RAM? It didn't happen with XP Pro, DXDiag always reported back the full amount of RAM.

Shouldn't they be using their own memory?

Low-end "integrated" graphics do actually "steal" RAM from the system, to lower costs. However, plug-in graphics cards have their own RAM, which they use.
The issue about not being able to use all 4GB of physical RAM in systems running 32-bit Win XP or 32-bit Vista is a separate issue and comes from the limit of 4GB of possible memory addresses in those OSes. Most motherboard and plug-in card hardware uses (relatively) small blocks of these addresses for their own purposes (not for general RAM), normally at the "top" of the 4GB address space. It's only after these addresses are allocated that the physical RAM is allowed to use the rest of the addresses. Depending on what MB and plug-in cards you have, the remaining addresses normally amount to 3-3.5GB, which can be used for physical RAM.

 

[fredgiblet]

the remaining addresses normally amount to 3-3.5GB, which can be used for physical RAM.

Unless you are crazy-rich and bought a pair of 768MB video cards...