Does PC133 underclock to PC100?

Mr_Flibbles

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Jul 27, 2002
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Hello. I recently bought a stick of 256MB PC133 RAM for a friend's Dell system. The computer (a Dimension L800R) only supports PC100 SDRAM, but it was considerably more expensive than the PC133, and I was positive I'd used PC133 RAM in a motherboard that was made for PC100 before. I put the stick in with the existing 128MB chip (non-parity, unbuffered) and the computer wouldn't boot (I wasn't able to identify the beep code). I also tried just putting the 256MB chip in, and it still wouldn't boot. I took the chip back to Best Buy and asked them about it, and one of the techies said PC133 RAM just recently stopped working in motherboards that only supported PC100.

Can somebody verify this for me so I know I don't just have a bad/Dell incompatible chip? Thanks.
 

TheMASK

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I am pretty sure that PC133 works well on a PC100 mobo. May be 128MB is the mobo's max limit. That cud explain why ur comp wont boot with 256MB stick. Do check for a BIOS update. But hang around here for a while before u try the BIOS update..

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Flinx

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Is the 256MB chip double sided?
Often these older Mobo require double sided chips.
Oh and looking arount eh net it seems like the L800R can take a max of 512MB but it should take a 256MB double sided chip.

Too tired to look.

Do I need error checking?
When choosing among ECC, parity, and non-parity memory, you need to match what is already in your system. You can tell which kind you have by looking at one of the modules currently in your system. Count the number of black chips on one module. If the number of chips can be evenly divided by three or five, you should buy ECC or parity (whichever is offered for your system). If not, you should buy non-parity.

<A HREF="http://www.crucial.com" target="_new">crucial selection </A>
<A HREF="http://www.crucial.com/crucial/pvtcontent/memorytype.asp?model=&memtype=CHOOSE" target="_new">crucial advice</A>
For example, if one of your modules has nine chips, you should buy ECC or parity. If one of your modules has eight chips, you should buy non-parity.

If you're building your own system, we recommend using non-parity parts unless you will be using your system as a server or have a need for error checking. ECC and parity parts are slower than non-parity parts.

The loving are the daring!<P ID="edit"><FONT SIZE=-1><EM>Edited by Flinx on 08/20/03 08:20 PM.</EM></FONT></P>
 

Crashman

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Read the first post in the Motherboard's forum, it's locked at the top. It describes the density limit for the BX chipset. The only 256MB modules supported by the BX chipset use 16 chips, 8 per side. It's cheaper for RAM companies to use 8 chips of twice that density, or even 4 chips of 4 times the density, so that cheap RAM won't work.

It has nothing to do with speed, the right kind of PC133 would work on that board even with an old Celeron (66MHz bus) processor.

Dell claims 128MB max per module. I don't know why, I had a fileserver running a 256 and two 128's with the same board.

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