128M memory reading as 32M

[Accessdabbler]

A friend wants me to fix his old Pentium 100 computer. He currently has a 32M RAM stick in it (16 chips). I bought a 128M stick (8 chips) and tried to put it in the motherboard.

After the installation, the BIOS read only 64M. I removed the 32M stick and put in the 128M stick and the BIOS read only 32M again.

Why is the 128M reading as 32M?

He bought this computer used so he doesn't have a manual but I believe the mobo is an Amptron P-8400C. I can't find the Amptron name on the mobo anywhere but according to the photo it looks the same. These mobos are supposed to support up to 384M of RAM.

 

[jsauce]

Well just suppose it doesn't support that much ram, it only supports a maximum of 32MB in each slot, basically the system is only using 32MB of ram per stick, no matter the size. You should go out and buy two 32mb sticks of 72 pinn edo if you can find it and deal with it only having 96mb of ram. You could also spend a little bit of money, trash the old motherboard and cpu and get something faster.

One thing you could do is reboot the computer and wait for the post to finish than when the bios info appears look toward the bottom and see if you find the motherboard and chipset info you can take that and see if you can find a bios update for it and maybe the newer bios update can support more memory. You will need a new bios chip like $10 if the bios doesn't support flashing. John D. Saucier
jsauce@magicguild.com
Certified Technician
Network Administrator

 

[Accessdabbler]

I thought that there might be a RAM size restriction but without a full manual, I can't be sure. There are 2 DIMM slots and 4 SIMM slots. 6 x 32 = 192 Megs of RAM so I think the maximum per slot would have to be at least 64M, not 32M (since the max supported is 384M).

I could flash the BIOS but I'm a little nervous to try that when I'm not 100% sure which motherboard I've got. I'm 99% sure but still....

Personally, I think it has to do with the chips. The 32M stick has 16 chips, the 128M stick has 8 on one side. Although I've recently completed a computer course, there was no mention of why this type of chip layout would be a problem. I have heard that older motherboards like the 16 chip memory layout, I just don't know why.

 

[jsauce]

Have you tried pair installing: Two equal ram chips? Like 2 32mb chips or 2 64mb chips or 2 128mb chips?

And I wasn't even considering dimm slots with a system that old.

The chip layout is really only based on the amount of memory in each little chip. Like 128mb of ram with 8 chips is 16mb of ram on each chip. Where the 32mb stick of ram with 16 chips is 2mb on each. John D. Saucier
jsauce@magicguild.com
Certified Technician
Network Administrator

 

[ANFPS26]

If you are in the USA and want to try 72 pin EDO SIMM sticks, here is about the cheapest price:

http://www.ocsystem.com/edosimm72pin.html

I've used both the 32MB and the 64MB in an old 486 and they work great.
Your motherboard probably won't accept the single sided RAM and needs the double sided chips. These EDO sticks are double sided. Even though my mother board should take up to 256MB it will only recognise 128MB. I assume this has something to do with the bios. I was happy with 128, so I didn't flash the bios. "A little knowledge is a dangerous thing....."