Made a mess of purchasing new memory - please help!

Hi,

Got 1gb memory PC, needed more memory for scanning large pics, so
bought 512mb module.

Fits very snuggly although strangely the plastic "ejector tabs" either
side of the DIMM bank won't snap back in to place to secure the new
memory module. (However I cannot push module in any further - it
appears to fit well enough.)

Booting up shows no extra memory though.

Running utility prog "Sandra" tells me for the "system memory
controller" section that I only have 2 memory slots, but the
motherboard has 3 DDR DIMM sites.

However, the motherboard manual says this (and this is where I think
I've messed up) "DIMM2 & DIMM3 are sharing"

Basically, I was hoping for 3 DIMM slots each having 512mb memory
modules giving me 1.5gb of memory. But I'm still left with just 1gb,
even though all 3 slots are filled.

What should I do?

Thanks, regards, dnw.

PS ~ I'm not sure if it's my imagination, but my PC seems noticeably
faster now, especially when handing large pic files, which is why I
bought the extra memory.

Strange. Or is it?

Previously Dot Net Developer <> wrote:
> PS ~ I'm not sure if it's my imagination, but my PC seems noticeably
> faster now, especially when handing large pic files, which is why I
> bought the extra memory.

> Strange. Or is it?

If the ''levers'' ind the side do not snap in, tnen the memory is
wrong. Or insterted wrong. Period. If you are lucky, then you have
not actually killed the memory chips. But you might have. I did this
once by inserting a mamory chip 180 degrees turned. Fortunately
I smelled the error immediately on turning the PC on, and only
one of 5 power tabs had burned off. It was still usable.

Morale: Don't turn a PC on when you are not totally sure the
memory is inserted correctly.

Arno

I got the "levers" issue fixed - I pulled out the memory module and
refitted it, this time correctly.

I have tested the new module and it works fine.

However, I am unable to have all three 512mb modules working together.
I can have any 2 working, but not all 3.

The error message I get is a serious blue screen message on bootup -

Your BIOS is not fully ACPI compliant. Please visit
www.hardware-update.com to update your BIOS.

I am going to check this out now...

Regards, dnw.

Successfully upgraded bios.

However, when I add the extra memory, I still get ACPI compliant error
message.

Wondering whether my mobo can handle ACPI - trouble is, can't see any
way of disabling it in the bios options on bootup. I can have either
state S1 or S3, but nothing else.

I have abit BD7II mobo. I have turned off all power management
features in XP.

Do I need a new mobo to be able to have 3 lots of 512mb? (Manual says
I can have max of 2gb, so I'm not hitting a limit in this regard)

Thanks, regards, dnw.

"Dot Net Developer" wrote

> Do I need a new mobo to be able to have 3 lots of 512mb? (Manual says
> I can have max of 2gb, so I'm not hitting a limit in this regard)

Found this at

http://www.futurehardware.in/188994.htm
"ABIT BD7II-RAID, max memory 2GB (in theory?)..."

The 845E Northbridge drives a maximum of four banks of
memory. A three slot motherboard has room for six banks of
memory, meaning, at any one time, only four of the six
banks have control signals available to drive them.

DIMM slot 0 is "normal" and can accept a double sided DIMM.

DIMM slots 1 and 2 are "crosswired", allowing one double
sided DIMM in DIMM slot 1 or two single sided DIMMs to be
used in slot 1 and slot 2.

845E Northbridge datasheet - PDF page 113
ftp://download.intel.com/design/chip...s/29074201.pdf

"Maximum of two DIMMs, single-sided and/or double-sided"

SCS0# -------- DIMM 0 side A

SCS1# -------- DIMM 0 side B

+----- SCS2# -------- DIMM 1 side A
|
| +-- SCS3# -------- DIMM 1 side B
| |
| +----------------- DIMM 2 side A
|
+-------------------- DIMM 2 side B

When you plug a single sided DIMM into the DIMM 1 slot, it uses
SCS2# chip select signal. A single sided DIMM in DIMM 2 slot uses
SCS3# chip select signal. If a chip select signal is used by
more than one side of a DIMM, chaos results. Plugging three
double sided DIMMs would cause that chaos.

Most people will use two double sided DIMMs on 845 based boards,
leaving the third slot unused, because there are no more chip
select signals left to address the third slot. And that is
why the motherboard has a limit of 2GB (2x1GB) stated in the
user mahual, as a third 1GB DIMM could not be accessed.

Good stuff. Thanks a lot.

I realise I cannot have 3 dimms. The manual is very poor and should
have warned me better. I have a spare 512 module I guess I could sell
on ebay!!

Cheers, dnw.

Previously Dot Net Developer <> wrote:
> I got the "levers" issue fixed - I pulled out the memory module and
> refitted it, this time correctly.

Ah, yes. Sometimes that is necessary.

> I have tested the new module and it works fine.

> However, I am unable to have all three 512mb modules working together.
> I can have any 2 working, but not all 3.

That is a typical limitation in todays systems. Often you can have
only 2 or 4 modules, but not 3. And they need to be identical pairs.

> The error message I get is a serious blue screen message on bootup -

> Your BIOS is not fully ACPI compliant. Please visit
> www.hardware-update.com to update your BIOS.

> I am going to check this out now...

I think that message is bogus.

Arno

Previously MasterBlaster <Nobody'> wrote:

> "Dot Net Developer" wrote

>> Do I need a new mobo to be able to have 3 lots of 512mb? (Manual says
>> I can have max of 2gb, so I'm not hitting a limit in this regard)

> Found this at

> http://www.futurehardware.in/188994.htm
> "ABIT BD7II-RAID, max memory 2GB (in theory?)..."

> The 845E Northbridge drives a maximum of four banks of
> memory. A three slot motherboard has room for six banks of
> memory, meaning, at any one time, only four of the six
> banks have control signals available to drive them.

> DIMM slot 0 is "normal" and can accept a double sided DIMM.

> DIMM slots 1 and 2 are "crosswired", allowing one double
> sided DIMM in DIMM slot 1 or two single sided DIMMs to be
> used in slot 1 and slot 2.

Urgh. This is really unlucky. Many miodern boards only
accept single-sided modules. Then you need to have pairs.
This special solution is unecessarily confusing and the
designers should be sacked for incompetence.

Arno



> 845E Northbridge datasheet - PDF page 113
> ftp://download.intel.com/design/chip...s/29074201.pdf

> "Maximum of two DIMMs, single-sided and/or double-sided"

> SCS0# -------- DIMM 0 side A

> SCS1# -------- DIMM 0 side B

> +----- SCS2# -------- DIMM 1 side A
> |
> | +-- SCS3# -------- DIMM 1 side B
> | |
> | +----------------- DIMM 2 side A
> |
> +-------------------- DIMM 2 side B

> When you plug a single sided DIMM into the DIMM 1 slot, it uses
> SCS2# chip select signal. A single sided DIMM in DIMM 2 slot uses
> SCS3# chip select signal. If a chip select signal is used by
> more than one side of a DIMM, chaos results. Plugging three
> double sided DIMMs would cause that chaos.

> Most people will use two double sided DIMMs on 845 based boards,
> leaving the third slot unused, because there are no more chip
> select signals left to address the third slot. And that is
> why the motherboard has a limit of 2GB (2x1GB) stated in the
> user mahual, as a third 1GB DIMM could not be accessed.

Previously Dot Net Developer <> wrote:
> Good stuff. Thanks a lot.

> I realise I cannot have 3 dimms. The manual is very poor and should
> have warned me better.

Agreed. This is unexpected behaviour. Not your fault.

> I have a spare 512 module I guess I could sell on ebay!!

Best option, I think.

Arno