P4x266 motherboard and 1G memory module

[newsposter]

Hi everybody

My motherboard's manual can be found here

http://www.via.com.tw/download/mainboards/3/5/p4xb-s-r_v1.3.pdf

The mothreboard is also described here

http://www.via.com.tw/en/products/chipsets/p4-series/p4x266/

Chipset
· VIA Apollo P4X266 chipset (VT8753 & VT8233)
- Supports Intel® Pentium® 4 processors with 400MHz (100MHz QDR) CPU
Front Side Bus (FSB).
- AGP v2.0 compliant with 8x transfer mode.
- High Bandwidth V-Link Client controller.
- Integrated Faster Ethernet LPC.
- Integrated Hardware Sound Blaster/Direct Sound AC'97 audio.
- Ultra DMA 33/66/100 master mode PCI EIDE controller.
- ACPI 1.0B and PCI Bus Power Management 1.1 compliant.
Main Memory
· 3 x 184-pin DDR DIMM slots.
· Supports up to 3GB of DDR266 SDRAM (PC2100/PC1600).
· Supports 2.5v DDR266 SDRAM.
*************************************************************************************

I have the following modules:

1G DDR266, PC100
Module banks: 1
Density 1024x2
Parity No Ecc no
Voltage: SSTL 2.5V/2.6V
Timming:Cycle 7.3 ns (CAS Latency 2.5)
Datawidth:Module: 0x64, Prim. SDRAM x0/x0

2X256M DDR266, PC100

Module banks: 2
Parity No Ecc no
Voltage: SSTL 2.5V/2.6V
Timming:Cycle 7.3 ns (CAS Latency 2.5)
Datawidth:Module: 0x64, Prim. SDRAM x0/x0

The problem:

The BIOS shows only 1GB of installed memory on the motherboard.
If I install only the 1G module the BIOS is reporting 512MB.

The manufacturer lists the module as compatible with

http://www.via.com.tw/en/products/chipsets/p4-series/p4x266a/

Question: what is the difference between p4x266 and p4x266a ?
Why is my memory module not seen entirely ?

Thank you

 

[Pen]

Hi everybody

My motherboard's manual can be found here

http://www.via.com.tw/download/mainboards/3/5/p4xb-s-r_v1.3.pdf

The mothreboard is also described here

http://www.via.com.tw/en/products/chipsets/p4-series/p4x266/

Chipset
· VIA Apollo P4X266 chipset (VT8753 & VT8233)
- Supports Intel® Pentium® 4 processors with 400MHz (100MHz QDR) CPU
Front Side Bus (FSB).
- AGP v2.0 compliant with 8x transfer mode.
- High Bandwidth V-Link Client controller.
- Integrated Faster Ethernet LPC.
- Integrated Hardware Sound Blaster/Direct Sound AC'97 audio.
- Ultra DMA 33/66/100 master mode PCI EIDE controller.
- ACPI 1.0B and PCI Bus Power Management 1.1 compliant.
Main Memory
· 3 x 184-pin DDR DIMM slots.
· Supports up to 3GB of DDR266 SDRAM (PC2100/PC1600).
· Supports 2.5v DDR266 SDRAM.
*************************************************************************************

I have the following modules:

1G DDR266, PC100
Module banks: 1
Density 1024x2
Parity No Ecc no
Voltage: SSTL 2.5V/2.6V
Timming:Cycle 7.3 ns (CAS Latency 2.5)
Datawidth:Module: 0x64, Prim. SDRAM x0/x0

2X256M DDR266, PC100

Module banks: 2
Parity No Ecc no
Voltage: SSTL 2.5V/2.6V
Timming:Cycle 7.3 ns (CAS Latency 2.5)
Datawidth:Module: 0x64, Prim. SDRAM x0/x0

The problem:

The BIOS shows only 1GB of installed memory on the motherboard.
If I install only the 1G module the BIOS is reporting 512MB.

The manufacturer lists the module as compatible with

http://www.via.com.tw/en/products/chipsets/p4-series/p4x266a/

Question: what is the difference between p4x266 and p4x266a ?
Why is my memory module not seen entirely ?

Thank you

The p4x266 is a Northbridge Chipset NOT the motherboard..
The A version would be the updated/upgraded version of same. Your
motherboard is P4XB-R or -S or -SA or -RA. In any case
Crucial calls for the same memory in all four. Since the 512 MB
seems to be fine, I can only conclude that the 1GB unit is
apparently higher density than the mobo supports as that is
the usual problem when you only get half the memory.
This quote from the 266A information would tend to support
my conclusions. See the *** marked bit.

The VIA Apollo P4X266A further expands VIA's extensive line
of Intel® Pentium® 4 chipsets. VIA now offers Pentium 4 platform
solutions from top to bottom, with the VIA ProSavage P4M266
offering SMA graphics for the low end, ***the VIA Apollo P4X266
offering mainstream discrete performance, and the new VIA
Apollo P4X266A covering the high end extreme performance segment.***