mb supports double-sided yet detects only half RAM

I know this is an outdated config, but it will be great if you could
help.

I'm trying to upgrade RAM on an assembled Pentium3 PC 1.1Ghz
Existing SDRAM was 128, I am trying to add another 256 but it detects
only 128 of the new 256

Motherboard M6TWG V2.0 - manual says it supports double sided SDRAM
with max board capacity of 512MB

The motherboard manual states:
DIMM memory bus frequency always run 100MHz, if you use SRAM PC 133
type


SDRAM HY57V28420AT-S , 256MB SDRAM, PC133, double sided
===========================================================
Config 1. BIOS POST only reports half the memory (128MB) when booting
up with single 256MB module

Config 2. BIOS POST only reports 256MB memory when booting up with
256MB module plus older 128MB module (same vendor, PC133)
===========================================================
With Config 2...
Windows 2000 System Infomation --> Hardware --> Memory reports

System Information report written at: 04/17/2004 09:48:23 PM
[Memory]

Range Device Status
0xCC000-0xCFFFF System board OK
0xF0000-0xF7FFF System board OK
0xF8000-0xFBFFF System board OK
0xFC000-0xFFFFF System board OK
0xFEF0000-0xFEFFFFF System board OK
0x0000-0x9FFFF System board OK
0x100000-0xFEEFFFF System board OK
0xFEE00000-0xFEE00FFF System board OK
0xFFB00000-0xFFB7FFFF System board OK
0xFFF00000-0xFFFFFFFF System board OK
0xE0000-0xEFFFF System board OK
0xA0000-0xBFFFF PCI bus OK
0xA0000-0xBFFFF Intel Corporation 810 Graphics Controller Hub OK
0xC0000-0xDFFFF PCI bus OK
0xFF00000-0xFFEFFFFF PCI bus OK
0xD0000000-0xD3FFFFFF Intel Corporation 810 Graphics Controller Hub OK
0xD6000000-0xD607FFFF Intel Corporation 810 Graphics Controller Hub OK
0xD5000000-0xD50000FF Realtek RTL8139(A) PCI Fast Ethernet Adapter OK

===============================================================
With Config 2...
Windows 2000 System Infomation --> Hardware --> IRQs

System Information report written at: 04/17/2004 09:51:04 PM
[IRQs]

IRQ Number Device
9 Microsoft ACPI-Compliant System
11 Realtek RTL8139(A) PCI Fast Ethernet Adapter
11 Intel(r) 82801AA USB Universal Host Controller
11 Intel(r) 82801AA SMBus Controller
11 AC'97 Driver for Intel(r) 82801AA Controller
14 Primary IDE Channel
15 Secondary IDE Channel
8 System CMOS/real time clock
13 Numeric data processor
6 Standard floppy disk controller
4 Communications Port (COM1)
12 PS/2 Compatible Mouse
1 Standard 101/102-Key or Microsoft Natural PS/2 Keyboard
10 MPU-401 Compatible MIDI Device

thanks
SN

 

Apparently a Biostar (i.e. not Asus) board with i810 or somesuch.

This memory chip is one of the 32Mx4 variant, which neither the i810 nor
the i440BX or i815 can address fully - you'd need a VIA 694X for that.
(BTW, electrically the module has only one "side" or rather bank with 16
* 4 = 64 bits width.) For this board you'd need a module with 16 chips
of 16Mx8 each, the kind that also works in BX boards.

Stephan

 

Org. Part Number Density Refresh Voltage Speed PKG
32Mx4 HY57V28420HCLT 128M 4K 3.3V 6/K/H/8/P/S 54 TSOP
32Mx4 HY57V28420HCT 128M 4K 3.3V 6/K/H/8/P/S 54 TSOP

(Same datasheet for both chips - The "L" is presumably low power.)
http://www.hynix.com/datasheet/pdf/dram/HY57V28420HC(L)T(0.2).pdf

Banks of memory are 64bits wide. On your DIMM, it takes all
16 chips, each of which is 4 bits wide, to make a bank. So,
even though the DIMM is "double sided", there is still only
a single bank of memory.

One of the differences between 32Mx4 and 16Mx8, is that the
second of the two needs one fewer address bit, to select a
location in memory. If a Northbridge is missing that address
bit, one of the symptoms is that only half the memory shows
up.

See page 42 of the following doc (the last entry in the table)
for the largest valid DIMM configuration. It shows as
(16) 16Mx8 chips. This is the datasheet for "82810-DC100 GMCH":
ftp://download.intel.com/design/chipsets/datashts/29065602.pdf

Your motherboard is actually a Biostar motherboard, and not made
by Asus. (The nearest Asus equivalent might be the MEW-AM,
not sure.) This Crucial page lists memory guaranteed to work
for a M6TWG:

http://www.crucial.com/store/listpa...rds&mfr=Biostar&cat=RAM&model=M6TWG&submit=Go

What is funny is, the fastest of the memory is also the cheapest
on that page, so return the DIMM you've got and spend $90 on
a stick of the good stuff.

HTH,
Paul

 

I wish the motherboard manual had included this little nugget of
compatibility information.

Thanks a lot Paul for your time and detailed explanation.
Thanks to you too Stephan.

-SN

 

Your motherboard was built - and the manual written - before the incompatible
dimms were being produced...

/daytripper