EP35C-DS3R/ Memory

Hi all.

I recently put together a system on a Gigabyte motherboard, model #
EP35C-DS3R. I wrote to their tech department with what I’m about to
ask here, but their answer wasn’t really satisfying to me, and didn’t
make much sense to my understanding of things. But who knows, it
could just be me!! :-)

I put in 4GB of Memory. It’s Corsair Memory:
2 X 2GB Modules
Twin 2 x 4096 - 6400C5DHX
800 MHz
5-5-5-18

I’m operating on Win XP Pro. When I go to My Computer and right-click
and choose Properties and bring up System Properties, it states that
my Memory is 2.75 GB of RAM.

Strangely enough, when I very first put the system together about a
week ago, I remember it had read 3 GB of RAM; currently, it is reading
2.75. I don’t know what has changed since a week ago.

I’ve been putting systems together since the mid/ late 90’s, and I was
aware at one time that if you have either a "cheap" motherboard and/
or memory sticks, that they may not always read correctly. Well, this
is a pretty decent motherboard and a good brand name of memory.

The instructions in the motherboard’s manual for memory installation
was a little chart, and it was slightly confusing. This board
actually has 6 slots for memory, but two of them are for DDR3 memory,
which I don’t have; I have DDR2. And, like many motherboards, the
slots are color-coded. Usually, when installing dual channel memory,
you put it in matching color slots; but not always...I’ve seen
motherboards that don’t do this.

But like I said, the instructions in the manual with the little chart
were slightly confusing, but I guess I did it correctly because here’s
how I described it to the tech people at Gigabyte:

"I have the two chips in the DDRII 1 and DDRII 3 slots; they are
colored Yellow. Is this correct? Is there something I need to check/
change in the BIOS? Should I try putting the chips in different slots?
I know to stay away from the DDRIII slots of 1 and 2; I don’t even
have that type of memory."

When they wrote back, they didn’t say that I had physically installed
it wrong. In my message to them I also mentioned that I have a BFG
GeForce 9800 GX2 Nvidia graphics card, so, they included something
about that in their reply. Anyway, here’s their reply:

"The GX2 card will reserve mroe memory, if using an single gpu card
it should be able to detect at 3.xxx
Due to standard PC architecture, a certain amount of memory is
reserved for system usage and therefore the actual memory size is less
than the stated amount."

I think there’s a type-o in their response where it says "mroe"; I
think they meant "more".

So what does their response mean? Are they saying that my graphics
card is "physically" demanding so it’s affecting my system RAM
reading (4GB reading as 2.75). And I know that some memory is used
for system usage, but is that going to affect the actual memory size
amount as reported in System Properties? Any other system I’ve put
together through the years....when I right-click on My Computer/
Properties, and then there’s System Properties.......it’s always read
the proper/ actual amount of Memory that I had installed physically in
my system. It didn’t report back to me the amount available at the
moment minus the amount being used by "system usage".

They didn’t comment on my suggestion of trying my two sticks of RAM in
different slots (the other two DDR2 slots; not the DDR3).

What do you think, everyone? Shouldn’t System Properties report back
the actual amount of RAM physically installed in the system?

Any help, hints, tips, or suggestions would be much appreciated.

Thanks,
Pez

Pez wrote:
Hi all.

I recently put together a system on a Gigabyte motherboard, model #
EP35C-DS3R. I wrote to their tech department with what I’m about to
ask here, but their answer wasn’t really satisfying to me, and didn’t
make much sense to my understanding of things. But who knows, it
could just be me!! :-)

I put in 4GB of Memory. It’s Corsair Memory:
2 X 2GB Modules
Twin 2 x 4096 - 6400C5DHX
800 MHz
5-5-5-18

I’m operating on Win XP Pro. When I go to My Computer and right-click
and choose Properties and bring up System Properties, it states that
my Memory is 2.75 GB of RAM.

Strangely enough, when I very first put the system together about a
week ago, I remember it had read 3 GB of RAM; currently, it is reading
2.75. I don’t know what has changed since a week ago.

I’ve been putting systems together since the mid/ late 90’s, and I was
aware at one time that if you have either a "cheap" motherboard and/
or memory sticks, that they may not always read correctly. Well, this
is a pretty decent motherboard and a good brand name of memory.

The instructions in the motherboard’s manual for memory installation
was a little chart, and it was slightly confusing. This board
actually has 6 slots for memory, but two of them are for DDR3 memory,
which I don’t have; I have DDR2. And, like many motherboards, the
slots are color-coded. Usually, when installing dual channel memory,
you put it in matching color slots; but not always...I’ve seen
motherboards that don’t do this.

But like I said, the instructions in the manual with the little chart
were slightly confusing, but I guess I did it correctly because here’s
how I described it to the tech people at Gigabyte:

"I have the two chips in the DDRII 1 and DDRII 3 slots; they are
colored Yellow. Is this correct? Is there something I need to check/
change in the BIOS? Should I try putting the chips in different slots?
I know to stay away from the DDRIII slots of 1 and 2; I don’t even
have that type of memory."

When they wrote back, they didn’t say that I had physically installed
it wrong. In my message to them I also mentioned that I have a BFG
GeForce 9800 GX2 Nvidia graphics card, so, they included something
about that in their reply. Anyway, here’s their reply:

"The GX2 card will reserve mroe memory, if using an single gpu card
it should be able to detect at 3.xxx
Due to standard PC architecture, a certain amount of memory is
reserved for system usage and therefore the actual memory size is less
than the stated amount."

I think there’s a type-o in their response where it says "mroe"; I
think they meant "more".

So what does their response mean? Are they saying that my graphics
card is "physically" demanding so it’s affecting my system RAM
reading (4GB reading as 2.75). And I know that some memory is used
for system usage, but is that going to affect the actual memory size
amount as reported in System Properties? Any other system I’ve put
together through the years....when I right-click on My Computer/
Properties, and then there’s System Properties.......it’s always read
the proper/ actual amount of Memory that I had installed physically in
my system. It didn’t report back to me the amount available at the
moment minus the amount being used by "system usage".

They didn’t comment on my suggestion of trying my two sticks of RAM in
different slots (the other two DDR2 slots; not the DDR3).

What do you think, everyone? Shouldn’t System Properties report back
the actual amount of RAM physically installed in the system?

Any help, hints, tips, or suggestions would be much appreciated.

Thanks,
Pez

Computers have an address space. All hardware must be mapped somewhere
in the address space.

When a 32 bit OS is used, the address space is 4GB. Now, the hardware
we desire to access, consists of 4GB of memory plus 1GB of GPU memory on
the 9800GX2 (2x512MB GPUs). This cannot all fit. So the PCI Express
and PCI busses are mapped to the top of the 4GB space. The PCI Express
component is 1GB, and the PCI bus would have a minimum allocation of
256MB. (The allocations seem to be in multiples of 256MB.)
4GB minus 1GB minus 256MB equals 2.75GB. That sounds about right.

What happened to the rest of the memory ? It is inaccessible. In
other words, when the processor issues an address, it is translated
as an access to a particular piece of hardware. Any number below
2.75GB, points into the memory sticks. Any number between 2.76GB and
4GB, points to a system bus or system resource or the like. It
means the DRAM cells above 2.75GB cannot be seen or touched
by the processor.

A 64 bit OS, would make more of the resources in your computer usable.
By means of memory remapping support in the BIOS and hardware, the
4GB of memory modules should all be visible in a 64 bit OS. There
are still limitations on how much memory any one individual process
can use (an OS limit).

This article explains it as well, if you want a second opinion.

March 08, 2007 "Dude, Where's My 4 Gigabytes of RAM?"
http://www.codinghorror.com/blog/archives/000811.html

If you unplugged the PCI Express 9800GX2, and install a mouldy
old PCI video card with 32MB of memory on it, chances are you'd
see 3.5GB of free memory reported.

Paul