[RESOLVED] RAM not being SEEN properly

[martin_morgan]

I have just installed an additional 64 Mb 100MHz DIMM chip to a Pentium 200MHz PC to supplement the 32Mb DIMM chip (of unknown speed) already on board.
Only an additional 16Mb is being read. If I install it on its own, again, it only registers as a 16Mb chip. Can anyone suggest why?

[Iverno]

Try installing the 64 Mb block in a different machine, and tjeck if it's the Ram.

There are som rules when you work with DIMM ram, tjeck your manual for settings.

[sdrawkcab]

Several Socket 5/7 chipsets had trouble reading some types of RAM. Intel Triton/430 chipsets and VIA vxpro were guilty of this. If your 64MB reads as 16, this is almost always the reason why. Go ahead and try the first suggestion, to put the RAM in another machine and test it. If it reads 64, you're SOL on the other machine. Try to find a PC66 DIMM, with 4K refresh or labeled "4-clk". This RAM works better with these motherboards.

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[Ya_know]

I am suprised you can even get the PC to boot! There are no standard pentiums (including you 200) chips that will run at 100mhz FSBus. Also, only motherboards that will support the much faster AMD socket 7 chips meant to run with that bus can support 100mhz DIMMs. You need to find 66mhz memory, plain and simple...

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[Antimatter]

<font face="Tahoma, Arial, Helvetica, Verdana, Geneva" size="2">Originally posted by Ya_know:
I am suprised you can even get the PC to boot! There are no standard pentiums (including you 200) chips that will run at 100mhz FSBus. Also, only motherboards that will support the much faster AMD socket 7 chips meant to run with that bus can support 100mhz DIMMs. You need to find 66mhz memory, plain and simple...

</font>

PC100 RAM works fine in most 66MHz FSB machines. A lot of PC133 does as well.

In answer to the question, I agree with sdrawkcab but check the mobo manufacturer website. There may be a BIOS upgrade available to allow the machine to recognise the correct amout of RAM.


[This message has been edited by Antimatter (edited October 09, 2001).]

[confus-ed]

Try a bios update for your motherboard, once upon a time 8Mb was a lot, and if my memory serves me right 16MB was as much as you could allocate to a bank hence why you only see 16MB out of 64MB, assuming it works in another machine ok.

Ya_Know doesn't (know!), if it fits in the slot it will run as fast as the slowest memory, by default, some bioses will let you run different memory speeds, but you need to have the fastest in slot 1 etc, but this is bad for stability.

[Ya_know]

<font face="Tahoma, Arial, Helvetica, Verdana, Geneva" size="2">Originally posted by confus-ed:
Ya_Know doesn't (know!)</font>

I may be wrong, but the important thing is that I believe that I am right. We will just have to see what happens...

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[godofuq]

<font face="Tahoma, Arial, Helvetica, Verdana, Geneva" size="2">Originally posted by Ya_know:
I may be wrong, but the important thing is that I believe that I am right. We will just have to see what happens...

</font>

Uh oh.... I think I came in to this discussion at the wrong time

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[Ruslan]

<font face="Tahoma, Arial, Helvetica, Verdana, Geneva" size="2">Originally posted by Antimatter:
PC100 RAM works fine in most 66MHz FSB machines. A lot of PC133 does as well.

In answer to the question, I agree with sdrawkcab but check the mobo manufacturer website. There may be a BIOS upgrade available to allow the machine to recognise the correct amout of RAM.
</font>

Agree with Antimatter. All depends on motherboard's chipset and BIOS update...
That topic has been already discussed many times here...
Even my ASUS P2B BX motherboard did not recognize PC133 128Mb stick correctly until I have updated BIOS.
Same things for an old motherboards... Beware, many of old VX, VIA VPx - based motherboards required only double-sided DIMMs (PC-66 or PC-100 - it doesn't really matter - but it should be double-bank memory,though)...

[Hippie_Techs]

I agree with Antimatter and disagree with Ya_know. PC-100 memory will default to PC-66 if that is what the motherboard is running at. Remember there really wasn't much difference between PC-100 and PC-66 chips, the PC-100's could just clock higher. Think of it as overclocked PC-66 memory. As far as the memory only being seen as 16MB, I haven't heard whether or not the memory has been tested in another machine yet. Can't really make a suggestion without some basic trouble shooting done. Do you get BSODs with the memory installed (an indication of an incompatability or failure of the memory.)? Are you 100% sure it is a 64MB DIMM?

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[The Real SlyVenom]

Symptom 34-14. When I install two 64MB SIMMs, only 32MB of RAM are displayed when I turn on the computer. The motherboard is probably using a 430VX chipset which (though supporting 128MB of RAM), will not support 64MB memory devices. The 430VX only supports the following memory devices:

512Kx32-bit (2MB)
1Mx32-bit (4MB)
2Mx32-bit (8MB)
4Mx32-bit (16MB)
The layout for a 64MB SIMM is 16Mx32-bit which isn't in the list shown above. When you install two 64MB SIMMs, the system will use the 4Mx32-bit specification to calculate the memory, thus displaying 32MB. Unfortunately, this is a limitation of the motherboard, and cannot be corrected without upgrading the motherboard.

[snappyone2u]

I am running PC133 on a 100mhz board, what gives?

[Tech666]

PC150 , 133 , 100 , 66 etc , only is the MAX RATED speed it can run at , and all are backwards compatable , IE 133 will run at 66 , what you have run into is the chipset not being compatable with the either the density of the chips , or the layout of the datapaths.

you will only see 16 meg of thaat dimm , and to be honest , its probably gonna casue problems.


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[server69]

sounds like someone needs some PC66 RAM...
and if it's a really old board, i'd check to see if it's one of those all to common ones that want EDO DIMM's, not SDRAM...but my money's on SDRAM

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[format c:]

I have seen this on an old board and it comes down to this " Memory density " , Your board cannot handle the high density dimms that are now out, You need to try to locate lower density memory, It does not really matter about the speed , memory will clock down to 66 mhz if it is pc 100 or pc 133
Talk to you local computer shop and see if they can get you some lower density memory, you may pay a bit more for it , Good luck

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