Missing system RAM, is Nvidia 8600m GT responsible?

My Vostro 1500 main specifications are as follows –

Intel Core 2 Duo 2.00Ghz
4Gb RAM
160Gb 7200rpm
Nvidia 8600M GT with 256Mb dedicated GDDR2

My problem is when I check amount of total RAM on both Vista and XP, it says the system has 3.5Gb RAM. And the Graphic adapter RAM is 512Mb. BIOS says there is 4Gb, also indicates some will be used for the system but does not say for what.

I do know that certain systems (depending on the system architecture) does not support/see up to 4Gb of RAM. But I’m not sure whether Vostro sees all 4Gb RAM or not.

Anyway, my main question is that I have lost 512Mb RAM from the system and Nvidia have got 512Mb instead of 256Mb.

1. Is the 8600M GT using the whole of missing RAM?
2. Or is it only using 256Mb as turbo cache and the rest as 256Mb dedicated GDDR2 ?

I think scenario 2 should be correct. If that’s so vostro does not see 256Mb out of 4Gb RAM. If scenario 1 is correct then vostro does see all 4 GB RAM but shares system RAM and does not have dedicated GDDR2 (which is very good reason for me to call DELL).

My guess is, The best person who would know the answer for this issue would be a one that owns a specification of Vostro laptop which has 2GB system RAM and Nvidia 8600M GT 256Mb. Because, Vostro definitely see 2Gb RAM so that we can get to know how 8600M GT behaves.

Thanks in advance.

 

Read the link in my sig on 64-bit.

 

Thanks man... No offense but Jalf reply for your guide made more sense. Thanks you for you guide anyway...

But my Nvidia question still remains... does 8600M GT still have its own 256 dedicated GDDR2? and only uses 256 turbo cache from the main RAM?

 

If you are using Vista, it can use up to over 1GB for turbo memory. It isn't normally subtracted from the system memory, and it is only used during gaming if needed to. And yes, it will always have 256MB of dedicated memory.

 

yes it has its own memory

 

Are you using Vista 64bit?

 

Thanks for the replies guys,

Which means if I had 2Gb Ram installed I would end up having (2048b – 256Mb = 1792Mb) system ram where as 256Mb is Turbo cache.

In my case (4Gb RAM) in simple terms I should have (4096Mb – 256Mb = 3840Mb) system ram where as 256Mb is Turbo cache. But I only see 3584Mb RAM. Which means 256Mb is gone missing. I guess 32bit theory which Lithus has described in his thread which has been much elaborated by Jalf in a later reply describes the mystery. 256Mb is been used as system resources.

So basically Vostro (with my hardware specification) can only see/access maximum of 3840Mb and because 256 is turbo cache I see 3584Mb RAM.

What do you guys think?

For later question – I first use Vista 32bit. It showed me 3.5Gb. Currently on XP pro 32bit same result. My system is not 64bit.

 

Yes, with a 32-bit operating system your not going to see any more than that, it doesn't really have much at all to do with your graphics card.

 

yeah, what odin said mate.

i have 4gb ram, same GPU as you, inspiron 1720. i get 3584? MB of system RAM, but it tells me i have approx. 1774MB total video memory in DXDiag. real weird. screenshot for all youse:



but yeah i think its normal .. well atleast i hope it is.

 

Thanks guys.. its good to know that this is a know issue for 4Gb RAM on 32bit systems...

btw.. is there a way we can control the amount of RAM used for turbo cache on Vostro 1500?

 

as far as im aware, it happens automatically... if the computer feels that the gpu needs it, and has the ram going spair, it will assign it automatically.
i may be wrong though.

 

It's automatic, I don't worry about it since the video card will always return the RAM after it's finished "borrowing" it for games and other applications.

 

wouldnt bother me if it didnt return the ram . be nice to have a 1.5GB GPU.

 

It's not really a theory or a mystery. Any high level programmer will tell you the BIOS is taking your extra memory for Device drivers and such.

 

you guys rock... thanks for the replies...

i did some research myself and now understand the whole concept.

anyway, there are rumors that Vista SP1 on 32bit system shows all 4Gb RAM if any installed. but i doubt whether the system could actually use all 4Gb.

cheers,

 

I'd like to see where you got this.

 

That's not necessarily true. In some instances the memory isn't in fact being used for anything, it's merely that those addresses are locked for system purposes, and thus their aren't enough 32-bit addresses left to assign to all of the RAM.

Presumably it's the rumor that PAE support has been enabled/fixed, which would allow for a full 4GB on a 32-bit system, such as is already seen on 32-bit 2003.

 

Not quite. Remember that MANY internal components need memory address space, not just video card memory. Things such as your PCI express bus, sound cards, Ethernet cards, Wifi cards, bluetooth cards, CD/DVD drives, etc will all need a little bit of memory allocation. This accounts for the extra missing memory.

 

but the real issue is why its happening only when you have 4Gb ? why not when you have 2Gb or so... i guess thats the interesting point. thats where Jalf's explanation comes in to play (check the first page of this thread... )

 

It's because no "memory" is being used up. Only the addresses are being used up. Those addresses are still being used up by your other devices and such when you have 2GB mem, however you don't notice it because there are still plenty of addresses left over to allocate to the RAM. It's only when you hit the 32-bit limit (there are only 4GB of distinct 32-bit addresses) that you notice the problem.

 

It's because BIOS allocates the memory address to device drivers starting at the TOP of the address space. That's why you don't see any "missing" memory until you hit the top of the 32 bit address space (4 GBs)

True. I was hoping a simple answer was enough, but you caught me simplifying things to far. There are parts of the address space that aren't used for anything at that time, but the OS locks it out.

Edit: Odin243 beat me to the punch there

 

Totally Agree... but StomeEffect mentioned

"Things such as your PCI express bus, sound cards, Ethernet cards, Wifi cards, bluetooth cards, CD/DVD drives, etc will all need a little bit of memory allocation. This accounts for the extra missing memory."

So, i just wanted point out that it address space not memory.

 

I'm sorry, I meant to say memory address allocation. I can see where that might lead to confusion.

 

cheers StormEffect...

just one last question.... anyone know if there is a nVidia utility or something that we could use to control the amount of turbo cache ?? i don't find any option that allows me to do this in the nVidia control panel or in system BIOS....

 

It's a hardware feature, not directly controllable by the end user. Not that you would want to anyway, as it's a very dynamic allocation.

 

In other words, the card will (should) only be turbocacheing main memory when it has run out of on board video ram. Otherwise, as long as the current game or program does not overflow the card's video ram, turbocacheing will not occur.

By allowing the card to cache system ram when it runs out of ram, you prevent the video card from having to thrash your hard drive page file, which would slow your performance down to an absolute crawl.

 

I see... many thanks to everyone... cheers guys !!!