P
Paul
RalfG wrote:
> Except that there is no DOS or any OS loaded at that point, the information
> displayed is output from the PC BIOS, and possibly the video card,
> diagnostic self check.
>
> "AW" <AW@discussions.microsoft.com> wrote in message
> news
AB3BA79-C24F-4C71-AA56-C79AC2C9F35B@microsoft.com...
>> Gerry
>> Quite possibly. As I said I am not very good with computers. I think it is
>> more likely Go's statement though further down the tree that the first
>> screen
>> I see when I boot up is the DOS screen which can only load a maximum 128MB
>> which I didn't know.
>> Right clicking 'My Computer' does show 512MB of RAM installed.
>> I had a problem some months ago when video games and sometimes other
>> applications locked up totally and I had to restart. I was advised on
>> another
>> forum (or possibly this one) to alter the BIOS setting 'DRAM Timing
>> Settings'
>> to an 'AGP Aperture Size' of 256MB i.e half my total RAM. Does this mean
>> thereforethat I have lost 256MB of my RAM before I even start computing?
>>
>> I will ask my original question again and hope that someone can answer it
>> now.
>> If I buy another 512MB stick of RAM will I see a big difference in
>> performance or hardly any? If I did buy the stick and installed it should
>> I
>> up the 'DRAM Timing Settings' to an 'AGP Aperture Size' of 512MB or leave
>> it
>> at 256MB.
>>
>> Many thanks again
>>
>> --
>> AW
>>
Yes, that could be the video BIOS string displaying. I have a couple FX5200 cards
here, and one of them does display a BIOS string on the screen, before anything
else appears. The video card BIOS (a chip on the video card holds that 64KB of
code) is what created and printed the info on the screen. That could be what
is confusing matters. My ATI card doesn't display anything before the BIOS POST
screen appears.
The motherboard in question, should have no problem with RAM sticks up to a size
of 1GB each. So it won't have a problem reading or using a 512MB stick of memory.
If buying 1GB sticks, don't buy them from Ebay, because Ebay is awash in some
cheap and cheerless 1GB DDR memory. If you wanted to buy 1GB DIMMs, they should
be branded memory bought somewhere other than Ebay. The DIMMs you buy should
use 64Mx8 memory chips (and that information will be hard to get from the vendor).
This is an example of a Kingston stick that uses 64Mx8 chips. Generally, branded
memory makers don't fool around with DIMMs made from 128Mx4 chips, so AFAIK,
1GB branded RAM will use 16 of the 64Mx8 chips.
"Sixteen 64Mx8 DDR400" - equals a 1GB module
http://www.valueram.com/datasheets/KVR400X64C3A_1G.pdf
Note - I didn't really want to write the following section, but I was unable
to find a good web page that explained it...
With regard to what an AGP Aperture is:
http://www.techarp.com/showFreeBOG.aspx?lang=0&bogno=32
"Please note that the AGP aperture is merely address space, not actual physical
memory in use. Although it is very common to hear people recommending that the
AGP aperture size should be half the size of system memory, that is wrong!"
The aperture is a maximum mapping for the system memory, for graphics use. If no
game is running, system memory is available as it normally would be, so the
aperture doesn't prevent the memory from being used in the normal way.
The operating system has to allocate it, for it to be used (the OS would not
want a collision of usages for the memory).
When you play a 3D game, the game will prefer to keep textures in the video card
onboard memory (for performance). If the textures are too large, then system RAM
can be used to hold them.
Memory can be fragmented, with no large chunks immediately available. The GART is
a translation device. It allows discontinuous pieces of memory, to occupy what
appears to the video card, to be contiguous memory. The OS allocates the memory
first, maps it in the GART, and the program requesting the memory also needs
normal access to the memory as well (virtual to physical translation).
The game program then puts textures in the discontinuous pieces of memory - when
the video card deals with the memory, it all appears to be one continuous piece
of memory, starting at a base address and extending up to the max size set in
the BIOS. The game has to tell the video card that there are some valid entries
in the memory, for it to be used.
The accesses of the video card, to the memory, are based on physical addresses
on the AGP bus. The video card doesn't have access to the virtual address space
that the OS and programs are using. That is why the GART is present - it is like
address translation for the usage of the video card. Physical to physical mapping.
So when an aperture is set in the BIOS, it is not an immediate allocation of
memory. It sets the maximum size of the "window" in the address space that
can be used for mapping system memory for graphics card usage. It is up to the
3D game, to decide how much system memory to use and when. There is a
limit as to how much physical memory is available, and a game designer has to
balance the requirements of stack and heap for the program, versus burning up
all the memory to hold textures. If necessary, texture caching can also be managed by
the game, via holding it on disk until it is required (like an MS flight sim might do).
But most games don't really want to do that, because of the glitch in game performance
if you had to go to the disk a lot while the game is in motion.
Section 5.3 on page 116 in this doc, has a picture of the aperture and mapping
feature that would be in the Northbridge.
http://web.archive.org/web/20030314...m/technology/agp/downloads/agp30_final_10.pdf
So if you are gaming on a machine with 512MB total memory, there really isn't a
lot of memory to go around. If a game is heavy in 3D textures, you'd hope they'd
fit in video card memory, so none of the 512MB system memory is needed for that.
What trimming down the aperture setting does, is prevents the game from mapping
more than that amount through the GART. But if a game is managing its resource usage,
it might not need to be whipped into shape or policed that way.
You can play with the aperture, but there is no guarantee it is going to do
anything useful. There are a number of web pages, where they chart the effects
of the setting. And maybe you can reach some conclusion based on looking at
a number of those articles. I just leave mine set at 64MB, which happened to
be the BIOS default (i.e. I'm too lazy to do the research
)
HTH,
Paul
> Except that there is no DOS or any OS loaded at that point, the information
> displayed is output from the PC BIOS, and possibly the video card,
> diagnostic self check.
>
> "AW" <AW@discussions.microsoft.com> wrote in message
> news
AB3BA79-C24F-4C71-AA56-C79AC2C9F35B@microsoft.com...>> Gerry
>> Quite possibly. As I said I am not very good with computers. I think it is
>> more likely Go's statement though further down the tree that the first
>> screen
>> I see when I boot up is the DOS screen which can only load a maximum 128MB
>> which I didn't know.
>> Right clicking 'My Computer' does show 512MB of RAM installed.
>> I had a problem some months ago when video games and sometimes other
>> applications locked up totally and I had to restart. I was advised on
>> another
>> forum (or possibly this one) to alter the BIOS setting 'DRAM Timing
>> Settings'
>> to an 'AGP Aperture Size' of 256MB i.e half my total RAM. Does this mean
>> thereforethat I have lost 256MB of my RAM before I even start computing?
>>
>> I will ask my original question again and hope that someone can answer it
>> now.
>> If I buy another 512MB stick of RAM will I see a big difference in
>> performance or hardly any? If I did buy the stick and installed it should
>> I
>> up the 'DRAM Timing Settings' to an 'AGP Aperture Size' of 512MB or leave
>> it
>> at 256MB.
>>
>> Many thanks again
>>
>> --
>> AW
>>
Yes, that could be the video BIOS string displaying. I have a couple FX5200 cards
here, and one of them does display a BIOS string on the screen, before anything
else appears. The video card BIOS (a chip on the video card holds that 64KB of
code) is what created and printed the info on the screen. That could be what
is confusing matters. My ATI card doesn't display anything before the BIOS POST
screen appears.
The motherboard in question, should have no problem with RAM sticks up to a size
of 1GB each. So it won't have a problem reading or using a 512MB stick of memory.
If buying 1GB sticks, don't buy them from Ebay, because Ebay is awash in some
cheap and cheerless 1GB DDR memory. If you wanted to buy 1GB DIMMs, they should
be branded memory bought somewhere other than Ebay. The DIMMs you buy should
use 64Mx8 memory chips (and that information will be hard to get from the vendor).
This is an example of a Kingston stick that uses 64Mx8 chips. Generally, branded
memory makers don't fool around with DIMMs made from 128Mx4 chips, so AFAIK,
1GB branded RAM will use 16 of the 64Mx8 chips.
"Sixteen 64Mx8 DDR400" - equals a 1GB module
http://www.valueram.com/datasheets/KVR400X64C3A_1G.pdf
Note - I didn't really want to write the following section, but I was unable
to find a good web page that explained it...
With regard to what an AGP Aperture is:
http://www.techarp.com/showFreeBOG.aspx?lang=0&bogno=32
"Please note that the AGP aperture is merely address space, not actual physical
memory in use. Although it is very common to hear people recommending that the
AGP aperture size should be half the size of system memory, that is wrong!"
The aperture is a maximum mapping for the system memory, for graphics use. If no
game is running, system memory is available as it normally would be, so the
aperture doesn't prevent the memory from being used in the normal way.
The operating system has to allocate it, for it to be used (the OS would not
want a collision of usages for the memory).
When you play a 3D game, the game will prefer to keep textures in the video card
onboard memory (for performance). If the textures are too large, then system RAM
can be used to hold them.
Memory can be fragmented, with no large chunks immediately available. The GART is
a translation device. It allows discontinuous pieces of memory, to occupy what
appears to the video card, to be contiguous memory. The OS allocates the memory
first, maps it in the GART, and the program requesting the memory also needs
normal access to the memory as well (virtual to physical translation).
The game program then puts textures in the discontinuous pieces of memory - when
the video card deals with the memory, it all appears to be one continuous piece
of memory, starting at a base address and extending up to the max size set in
the BIOS. The game has to tell the video card that there are some valid entries
in the memory, for it to be used.
The accesses of the video card, to the memory, are based on physical addresses
on the AGP bus. The video card doesn't have access to the virtual address space
that the OS and programs are using. That is why the GART is present - it is like
address translation for the usage of the video card. Physical to physical mapping.
So when an aperture is set in the BIOS, it is not an immediate allocation of
memory. It sets the maximum size of the "window" in the address space that
can be used for mapping system memory for graphics card usage. It is up to the
3D game, to decide how much system memory to use and when. There is a
limit as to how much physical memory is available, and a game designer has to
balance the requirements of stack and heap for the program, versus burning up
all the memory to hold textures. If necessary, texture caching can also be managed by
the game, via holding it on disk until it is required (like an MS flight sim might do).
But most games don't really want to do that, because of the glitch in game performance
if you had to go to the disk a lot while the game is in motion.
Section 5.3 on page 116 in this doc, has a picture of the aperture and mapping
feature that would be in the Northbridge.
http://web.archive.org/web/20030314...m/technology/agp/downloads/agp30_final_10.pdf
So if you are gaming on a machine with 512MB total memory, there really isn't a
lot of memory to go around. If a game is heavy in 3D textures, you'd hope they'd
fit in video card memory, so none of the 512MB system memory is needed for that.
What trimming down the aperture setting does, is prevents the game from mapping
more than that amount through the GART. But if a game is managing its resource usage,
it might not need to be whipped into shape or policed that way.
You can play with the aperture, but there is no guarantee it is going to do
anything useful. There are a number of web pages, where they chart the effects
of the setting. And maybe you can reach some conclusion based on looking at
a number of those articles. I just leave mine set at 64MB, which happened to
be the BIOS default (i.e. I'm too lazy to do the research
)HTH,
Paul