quick memory question....

[Matthew]

I have a stick of Samsung memory and the sticker on the memory clearly
says 512MB DDR PC2100 but when I install it in my friend's Dell I am working
on it only shows up as 256... I've ran Memtest and it reports no errors and
this memory checks out for the Dell according to Crucial's website... is
there any other reason I am missing to explain why this isn't showing up as
512 in the computer?

 

[Paul]

I have a stick of Samsung memory and the sticker on the memory clearly
says 512MB DDR PC2100 but when I install it in my friend's Dell I am working
on it only shows up as 256... I've ran Memtest and it reports no errors and
this memory checks out for the Dell according to Crucial's website... is
there any other reason I am missing to explain why this isn't showing up as
512 in the computer?

There are a couple ways you could make a 512MB DIMM. You could use
(8) 64Mx8 chips or (16) 32Mx8 chips. Perhaps the memory controller
on the motherboard, is only capable of handling 32Mx8 chips ? When
the "deeper" memory array shows up, like the (8) 64Mx8 single sided
case, it is being "half addressed" by the limitations of the memory
controller.

When Crucial lists "512MB", the module they're selling might also
be composed of the correct kind of chips for the job. Crucial
is under no obligation to explain "memory density" to you. Which
is one of the dangers of reading the Crucial site, seeing "512MB"
and assuming any old 512MB module will work. There are certain
chipsets, with known "density issues", and we rely on the bad
experiences of others, to detect these situations.

If you mention the Dell model number, like "Dell Dimension 4400", it
makes it easier to research the details.

Paul

 

[Jan Alter]

There are a couple ways you could make a 512MB DIMM. You could use
(8) 64Mx8 chips or (16) 32Mx8 chips. Perhaps the memory controller
on the motherboard, is only capable of handling 32Mx8 chips ? When
the "deeper" memory array shows up, like the (8) 64Mx8 single sided
case, it is being "half addressed" by the limitations of the memory
controller.

When Crucial lists "512MB", the module they're selling might also
be composed of the correct kind of chips for the job. Crucial
is under no obligation to explain "memory density" to you. Which
is one of the dangers of reading the Crucial site, seeing "512MB"
and assuming any old 512MB module will work. There are certain
chipsets, with known "density issues", and we rely on the bad
experiences of others, to detect these situations.

If you mention the Dell model number, like "Dell Dimension 4400", it
makes it easier to research the details.

Paul

When installing memory it is important to check the specs on the mb to see
what chips are supported and in what configurations are acceptable to get
full compatability. Some mbs will only support chips of a certain density,
memory on one side of the module rather than two sides. I've run into your
exact situation with 128 mb chip only showing up as 64. If possible get a
hold of the the manual for the mb and see if you can find the memory
requirements.

 

[Matthew]

When installing memory it is important to check the specs on the mb to see
what chips are supported and in what configurations are acceptable to get
full compatability. Some mbs will only support chips of a certain density,
memory on one side of the module rather than two sides. I've run into your
exact situation with 128 mb chip only showing up as 64. If possible get a
hold of the the manual for the mb and see if you can find the memory
requirements.

Well it's an older Dell 4550 and he doesn't have any of the paperwork/disks
that came with the tower. He doesn't even have the service tag (the front
face of the case is missing).

The only thing I could find on Dell's site was:

 

[Matthew]

Well it's an older Dell 4550 and he doesn't have any of the
paperwork/disks that came with the tower. He doesn't even have the service
tag (the front face of the case is missing).

The only thing I could find on Dell's site was:

Sorry... I tried to paste and must have hit the shortcut to send?!?

Architecture DDR SDRAM
Memory connectors two
Memory capacities 128-, 256-, and 512-MB non-ECC DDR
SDRAM
Minimum memory 128 MB
Maximum memory 1 GB
Memory type DDR 333 (non-ECC) only on computers
with 533-MHz system clock speed
DDR 266 (non-ECC) on computers with
either 400- or 533-MHz system clock speed
BIOS address F8000h

His is the 400 MHz clock speed....

 

[Paul]

Sorry... I tried to paste and must have hit the shortcut to send?!?

Architecture DDR SDRAM
Memory connectors two
Memory capacities 128-, 256-, and 512-MB non-ECC DDR
SDRAM
Minimum memory 128 MB
Maximum memory 1 GB
Memory type DDR 333 (non-ECC) only on computers
with 533-MHz system clock speed
DDR 266 (non-ECC) on computers with
either 400- or 533-MHz system clock speed
BIOS address F8000h

His is the 400 MHz clock speed....

Kingston says the chipset is 845PE (that would be the Northbridge, which
connects to the memory). The Dell site says the same thing.

http://www.ec.kingston.com/ecom/configurator_new/modelsinfo.asp?SysID=12595

845PE chipset spec. See page 11 for starters.

http://www.intel.com/Assets/PDF/datasheet/251924.pdf

"System Memory Controller
-One 64-bit wide DDR SDRAM data channel
-Up to 2.0 GB of 266/333 MHz DDR SDRAM [ 2 slots times 1GB each ]
-Bandwidth up to 2.7 GB/s (DDR333)
-64-Mb, 128-Mb, 256-Mb, and 512-Mb SDRAM technologies
-Supports only x8 and x16 SDRAM devices with four banks [ memory chip device width ]
-Unbuffered, unregistered 184-pin non-ECC DDR SDRAM DIMMs only
-Two DDR DIMMs, single-sided and/or double-sided
-Does not support double-sided x16 DDR DIMMs
-JEDEC DDR DIMM specification configurations only
-Opportunistic refresh
-Up to 16, simultaneously open pages
-SPD (Serial Presence Detect) scheme for DIMM detection
-Suspend-to-RAM support using CKE
-Selective Command-Per-Clock (selective CPC) accesses"

"512-Mb SDRAM" means a 64Mx8 memory chip would work. So even a 512MB
module made with (8) 64Mx8 chips would work. Or a 1GB module made
with (16) 64Mx8 chips would work as well.

It looks to me, like "any old 512MB DDR DIMM" would work. I would
test the DIMMs, one at a time, and see if they respond correctly
that way.

You can also use CPUZ to check what the DIMM SPD is claiming,
once the system is booted. And the "Save Report" option, the
last tab over, will make it possible to get the contents of the
SPD table coming from the DIMM. That is what the BIOS uses to
figure out what was inserted into the computer.

http://www.cpuid.com/cpuz.php

Memory SPD
-------------------------------------------------------------------------

DIMM # 1

SPD registers
00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00 80 08 08 0E 0A 61 40 00 05 30 45 00 82 08 00 00
10 0C 04 38 01 02 00 03 3D 50 50 60 3C 1E 3C 2D 80
20 20 27 10 17 3C 1E 1E 00 00 3C 69 80 18 22 00 00
...

By decoding that table of 256 bytes of information, it is possible
to discover what the DIMM manufacturer thinks the module is. Each
module should have its own table. In some cases, DIMMs ship with
the wrong table burned into the SPD EEPROM on the DIMM Which
questions the competency of some people, to be making DIMMs. The
reason they can get away with that kind of carelessness, is the
BIOS is actually more clever than that, and has a second algorithm
for determining memory size.

Paul

 

[Matthew]

Sorry... I tried to paste and must have hit the shortcut to send?!?

Architecture DDR SDRAM
Memory connectors two
Memory capacities 128-, 256-, and 512-MB non-ECC DDR
SDRAM
Minimum memory 128 MB
Maximum memory 1 GB
Memory type DDR 333 (non-ECC) only on computers
with 533-MHz system clock speed
DDR 266 (non-ECC) on computers with
either 400- or 533-MHz system clock speed
BIOS address F8000h

His is the 400 MHz clock speed....

Kingston says the chipset is 845PE (that would be the Northbridge, which
connects to the memory). The Dell site says the same thing.

http://www.ec.kingston.com/ecom/configurator_new/modelsinfo.asp?SysID=12595

845PE chipset spec. See page 11 for starters.

http://www.intel.com/Assets/PDF/datasheet/251924.pdf

"System Memory Controller
-One 64-bit wide DDR SDRAM data channel
-Up to 2.0 GB of 266/333 MHz DDR SDRAM [ 2
slots times 1GB each ]
-Bandwidth up to 2.7 GB/s (DDR333)
-64-Mb, 128-Mb, 256-Mb, and 512-Mb SDRAM technologies
-Supports only x8 and x16 SDRAM devices with four banks [
memory chip device width ]
-Unbuffered, unregistered 184-pin non-ECC DDR SDRAM DIMMs only
-Two DDR DIMMs, single-sided and/or double-sided
-Does not support double-sided x16 DDR DIMMs
-JEDEC DDR DIMM specification configurations only
-Opportunistic refresh
-Up to 16, simultaneously open pages
-SPD (Serial Presence Detect) scheme for DIMM detection
-Suspend-to-RAM support using CKE
-Selective Command-Per-Clock (selective CPC) accesses"

"512-Mb SDRAM" means a 64Mx8 memory chip would work. So even a 512MB
module made with (8) 64Mx8 chips would work. Or a 1GB module made
with (16) 64Mx8 chips would work as well.

It looks to me, like "any old 512MB DDR DIMM" would work. I would
test the DIMMs, one at a time, and see if they respond correctly
that way.

You can also use CPUZ to check what the DIMM SPD is claiming,
once the system is booted. And the "Save Report" option, the
last tab over, will make it possible to get the contents of the
SPD table coming from the DIMM. That is what the BIOS uses to
figure out what was inserted into the computer.

http://www.cpuid.com/cpuz.php

Memory SPD
-------------------------------------------------------------------------

DIMM # 1

SPD registers 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00 80 08 08 0E 0A 61 40 00 05 30 45 00 82 08 00 00
10 0C 04 38 01 02 00 03 3D 50 50 60 3C 1E 3C 2D 80
20 20 27 10 17 3C 1E 1E 00 00 3C 69 80 18 22 00 00
...

By decoding that table of 256 bytes of information, it is possible
to discover what the DIMM manufacturer thinks the module is. Each
module should have its own table. In some cases, DIMMs ship with
the wrong table burned into the SPD EEPROM on the DIMM Which
questions the competency of some people, to be making DIMMs. The
reason they can get away with that kind of carelessness, is the
BIOS is actually more clever than that, and has a second algorithm
for determining memory size.

Paul

Thanks, I'll give CPUZ a try!