how do I get my PC to recognise new memory?

[showman]

Hi I am currently upgrading a pc for a friend and I'm having a problem with upgrading memory. I am upgrading the memory of a P166 computer which contains a Intel Triton VX chipset (Socket 7 based m/b) and an SM5 award bios. In fact although I have checked the bios number, the motherboard is clearly marked as: AB-SM5 i.e. an Abit SM5 The board had previously 4 edo ram adding up to 32 Mb of memory. I replaced this with a single SDRAM 128Mb and removed the edo ram. The computer works and on bootup shows the recognition of the SDRAM, but only counts 32 Mb not 128Mb. I have been told by friends that this may be due to the SDRAM being 100Mhz and at the time the motherboard was built only 66Mhz SDRAM was in existance, I was also advised that updating the bios may solve this problem (i.e. the board would recognise 100Mhz SDRAM. I have tried several bios updates from the Abit web site, but althought they install ok there is no difference to the memory allocation. (There is nothing wrong with the memory chip as I have tested it in another computer). Unfortunatley there is no manual with the motherboard and there doesn't appear to be any jumpers to set the memeory on the board. Does this mean there is no solution except to try and find some 66Mhz SDRAM (hard to find now) or is there some other way (i.e. a utility or bios upgrade that solves this)? I have emailed Abit to see if they can help and awaiting a reply, but if anybody here can help I would be very grateful. Any help appreciated. Showman

[Sensei]

The 100Mhz rating of the DRAM is just the maximum speed at which you can operate the RAM reliably. It will operate at lower frequencies. I suspect that if the computer can recognize it as 32 megs, then it is accessing the RAM, but not reading the size properly. If the 128 meg DIMM is EDO, try mixing it with the old memory (assuming they have the same pin count- you can't mix 'em!) or another 128M dimm. If it recognizes the additional memory, then the motherboard or bios may not be able to access more than 32 megs/slot. A last thought, which is a long shot- have you tried clearing the CMOS?

[showman]

Thanks Sensei, in fact I got a reply from Abit and it confirms what you said about being limited to 32Mb per memory slot, this apparantly is because 32Mb was the largest at the time the motherboard was made and due to the way the voltages were set (i.e. limitations of the motherboard) no bios upgrades were made to account for new memory. Thanks again for your time.

[marks]

Some further information: It can sometimes depend on the design of the memory module. I recently bought a 128Mb 100Mhz DIMM to put in my computer (a PII266, so it came with a 66Mhz DIMM). Upon insertion only 64Mb was recognised. Back in the shop their test machine detected a full 128Mb. They just gave me a different DIMM - same spec, but different design - and it is working fine. Crazy.

[htrfocus]

Showman, I have an AB-SM5 with the very same problem. Using the 60 pin EDO RAM the POST (and windows) count the correct amount of installed memory, but using a single 128MB strip of SDRAM (PC133) the POST only shows 32MB. I tried a strip of 64MB which showed 16MB, then a 32MB strip which showed 8MB. Whatever the size memory, it shows only 1/4 of it (the same as your case). I have a thread started on Abit's forum, but I've had no luck yet. Perhaps this 1/4th multiplier will spark an idea for someone.

- Justin