Problems installing RAM

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View
I am trying to upgrade the RAM on my PC from 512MB to 1GB.

I have 3 slots on my motherboard and after doing Crucial's memory
scan and looking at their recommendations I decided to add one 512MB
RAM module to my two existing 256MB modules. I first put it into the
third and only empty slot and turned the computer on. It booted up fine

but reported that there was still only 512MB. I moved the new 512MB to
the first slot and one of the 256MB to the third slot. This time it
reported that there was 768MB or RAM.

At least I know that the new RAM works. I am wondering if there is a
problem with the third slot. Is there anyway of finding out about this?

One thing I did notice was the inside of the computer was extremely
dusty. Is there a safe way of cleaning it? Could it be that some dust
is blocking one of the connections in the third slot? (It has been open

the whole time I have had the computer)

Thanks for any help


Re: Problems installing RAM wrote:
Quoted text here. Click to load it

What motherboard is it ?

It sounds like one of those four bank Northbridge controllers.
There appear to be three memory slots, but the slots are a bit
special. The first slot supports a double sided module.
The second slot may support a double sided module, or the
second and third slot may take a single sided module each.
The total number of "sides" is limited to four, by the design
of the Northbridge.

But unless you reveal the secret identity of the motherboard,
we'll never know for sure.

There is no reason to be worried about dust, until technical
explanations can be eliminated first.

One of the issues with dust, is a stream of dust particles
in moving air, can generate static electricity. If the source
of cleaning air is extremely dry, then there is a danger of
generating local static. Some sources of high pressure air,
are drier than others.


Re: Problems installing RAM

Thanks for that,

I am not sure of the name of the motherboard (being a real novice at
this). Where should I be looking for the name of the motherboard. I
guess it varies from motherboard to motherboard right? I will have a
look later. If it is any help I have an AMD Athlon + processor.



Re: Problems installing RAM wrote:
Quoted text here. Click to load it

Install this. Then look under Computer:DMI:Motherboard or
Motherboard:Chipset:Northbridge to get some specifics.
(Everest is the former AIDA32 program, a tool that provides
some ID info about computer gear.)

On name brand motherboards, there will be a model number and
the brand, printed in white letters on the motherboard itself.

If it is an Athlon, then my first theory won't be correct,
as that anomaly is for a particular Intel chipset.


Re: Problems installing RAM

On Fri, 12 Jan 2007 02:49:25 -0800, zeidman thoughtfully wrote:

Quoted text here. Click to load it

You may be able to read the name off the motherboard.  Or your PCs manual
may list the motherboard.   On the other hand your manual might tell you
how to configure memory for your PC.   I've found the low-end Crucial
memory doesn't coexist very well with other vendors memory.  

Re: Problems installing RAM

So I installed Everest and got the following results for the

--------[ Motherboard

    Motherboard Properties:
      Motherboard ID
62-0821-001131-00101111-040201-SiS746$M848A_M848A RELEASE 08/21/2003
      Motherboard Name                                  PCChips M848A

    Front Side Bus Properties:
      Bus Type                                          DEC Alpha EV6
      Bus Width                                         64-bit
      Real Clock                                        100 MHz (DDR)
      Effective Clock                                   200 MHz
      Bandwidth                                         1600 MB/s

    Memory Bus Properties:
      Bus Type                                          DDR SDRAM
      Bus Width                                         64-bit
      Real Clock                                        133 MHz (DDR)
      Effective Clock                                   267 MHz
      Bandwidth                                         2133 MB/s

    Chipset Bus Properties:
      Bus Type                                          SiS MuTIOL
      Bus Width                                         16-bit

    Motherboard Physical Info:
      CPU Sockets/Slots                                 1 Socket 462
      Expansion Slots                                   5 PCI, 1 AGP, 1
      RAM Slots                                         3 DDR DIMM
      Integrated Devices                                Audio, LAN
      Form Factor                                       ATX
      Motherboard Size                                  190 mm x 300 mm
      Motherboard Chipset                               SiS748

    Motherboard Manufacturer:
      Company Name                                      Elitegroup
Computer Systems
      Product Information
      BIOS Download

and then under the chip set:

--------[ Chipset

  [ North Bridge: SiS 748 ]

    North Bridge Properties:
      North Bridge                                      SiS 748
      Revision                                          10
      In-Order Queue Depth                              7

    Memory Timings:
      CAS Latency (CL)                                  2.5T
      RAS To CAS Delay (tRCD)                           3T
      RAS Precharge (tRP)                               3T
      RAS Active Time (tRAS)                            6T

    Memory Slots:
      DRAM Slot #1                                      256 MB  (DDR
      DRAM Slot #2                                      512 MB  (DDR

    AGP Controller:
      AGP Version                                       2.00
      AGP Status                                        Disabled
      AGP Device                                        nVIDIA GeForce2
      AGP Aperture Size                                 128 MB
      Supported AGP Speeds                              1x, 2x, 4x, 8x
      Fast-Write                                        Not Supported
      Side Band Addressing                              Supported,

    Chipset Manufacturer:
      Company Name                                      Silicon
Integrated Systems Corporation
      Product Information
      Driver Download

    Problems & Suggestions:
      Problem                                           AGP is
disabled. This may cause performance penalty.

There is indeed a reference to Northbridge..

I tried to find the manual from the link but couldn't find my
motherboard there.

Any help really appreciated


Re: Problems installing RAM wrote:
Quoted text here. Click to load it
Quoted text here. Click to load it

PCChips is a low end maker, but more than that, you apparently have
version 2.1 with 3 DIMM sockets. Manual is found here.

However, this board apparently had problems with 3 memory sockets as the
later version 5.0 has only 2 DIMMs.

Re: Problems installing RAM wrote:
Quoted text here. Click to load it
Quoted text here. Click to load it
Quoted text here. Click to load it
Quoted text here. Click to load it
Quoted text here. Click to load it

It is a SIS748 Northbridge, driving three slots.

There seem to be no particular restrictions to that chipset, and
the Crucial selector is showing a lot of different sizes of memory
will work.

At PC2100 rates, on a chipset rated for PC3200, there really should
not be a problem running three sticks. Even with the bus loading,
it should be easy for the chipset to drive them.

First thing I would recommend, is getting a copy of memtest86+ from . The downloaded program can either format a blank floppy,
and it makes a self-booting test floppy. Or there is an ISO version,
suitable for burning a bootable CD. While the test runs forever, you
only need to run it for two passes (pass counter is on-screen).

I would start with the new 512MB stick by itself. Install it in each
socket in succession and test it. See whether 512MB is reported in
each case. See if it will do even one pass clean. Then you'd know
whether each socket is OK.

The wiping action, of the memory contact against the contact surface
of the DIMM slot, should perform as much cleaning action as is needed.
For example, if the memory module has a gold plating on the contacts,
then applying abrasive cleaning to the contacts, merely removes the
"good" gold, exposing the less noble metal underneath. Gold does not
oxidize, but the underlying metal can.

In terms of sizing the memory, two methods can be used. The SPD chip
on the DIMM, contains timing info, and size info. The BIOS reads the
SPD chip, via the SMBUS serial bus. All three DIMMs would be read,
and timing numbers suitable for the slowest module, are used for
all three.

The BIOS also has the opportunity to test the memory for size. The
BIOS, if they design it that way, can write and read back, "searching"
for the end of memory. Sometimes, the SPD says one thing, and a
"size test" concludes something else. A "size test" might fail, if
one of the write/readback operations fails. That is a potential reason
for memory to be a different size, than as shown in the SPD>

On some chipsets, the memory controller has a limited number of address
bits. Using a memory which needs more address bits than the controller
has, causes only a portion (like half) of a stick to show up. Again,
the size test in the BIOS, may lead to the BIOS reporting only half
the size. That is typically referred to as a "density problem". In the
available info for the SIS748, I see no reason to suspect such a
problem. If you were using 1GB DIMMs (larger than anything you've
currently got), I'd be asking you if the modules had 128Mx4 chips
on them (for example, Nforce2 cannot handle such a chip, according to

So, there isn't an easy technical explanation for what you've seen so
far. Now, your test procedure, is to determine whether this is a module
problem or a socket problem. You start with one stick, and move
it through all the slots. That proves the contacts in each socket work.
You can repeat with the other two modules, on the off chance that one
of them has a contact problem. The final test, of installing all three,
is the "bus loading" test case, where you are checking to see if the
Northbridge can drive three sticks properly. At PC2100 rates, there
should not be a problem doing that.

Another case to consider, is a "stupid BIOS". You might change the
order of the three sticks in the sockets. Try the 512MB nearest
the processor as one test case. Try the 512MB furthest from the
processor, as a second test case. Some BIOS have been known to
have parsing/setup problems, where they confuse easily. The BIOS
parses the modules in order, and depending on which module it
processes first, the BIOS can reach a different conclusion for
the settings, than if the modules are installed in another order.
Sometimes a BIOS upgrade, if one is available, will change the
symptoms seen.

I presume all three memories are PC2100 and unbuffered memory. As
otherwise, you would not have got a proper report of 512MB with the
2x256MB config, and 512MB reported for the single stick.

So more testing may help identify where the problem is.

Good luck,

Re: Problems installing RAM


I have not done all the testing yet as you suggest I just wanted to
give you some more info.

In Everest under SPD it gives reports for DIMM1 and DIMM3 (no DIMM2). 1
is the 256 MB module that is PC2100 and 3 is the 512MB is PC3200.

The manual says:

This motherboard accommodates three 184-pin 2.5V unbuffered
Double Data Rate (DDR) SDRAM memory modules. The memory
chips must be standard or registered SDRAM (Synchronous
Dynamic Random Access Memory). You can install 3 unbuffered
DIMM DDR 266/333 or 2 unbuffered DIMM DDR 400. Each
module can be installed with 32 MB to 1 GB of memory; total
memory capacity is 3 GB.

Originally I thought that this was a problem but now it does not seem
so as they are not all DDR 400 (I am assumeing that DDR400 and PC3200
are equivalent - or have I totally misunderstood things?)



Re: Problems installing RAM wrote:
Quoted text here. Click to load it

CPUZ ( has a "dump" facility, and it can dump the SPD for each
DIMM. You could try the DIMMs one at a time, and extract the table
below and post it. I'm not promising anything, but perhaps there
is some clue in there as to what is going on.

    Dump Module #1
          0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
    00   80 08 07 0D 0A 02 40 00 04 50 60 00 82 08 00 01
    10   0E 04 08 01 02 20 00 00 00 00 00 3C 28 3C 28 40
    20   60 60 40 40 00 00 00 00 00 00 00 00 00 00 00 00
    30   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 AC

This is an example of the document I use to decode the table:


Re: Problems installing RAM

Clean the dust out of the inside of your computer using a can of compressed
air, available at any computer shop.


Quoted text here. Click to load it

Site Timeline