Is PC133 Memory backwards compatible to PC100 slot? {SOLVED}

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Chum

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I put a stick in...(256) and macine only counts it as 128...what gives. I was told PC133...would work in PC100 boards. Was I lied to?
 
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No you weren't lied to usually it is backward compatible, I mean if your car can go 60mph then it can definately do 40mph same thing PC133 can do PC100 however is this memory registered?

Registered RAM reports itself to the mobo as half what it is so that the mobo can access it since the mobo cannot handle the number of addressess needed to access that much memory and so registered dimms take care of the addresses themselves but to make the mobo happy they only tell it "I'm half what I am".

This could be the problem, I tried to get some registered memory for my old i440BX mobo but it didnt' work the memory only reported half what it was and I was only able to use half of what I had it must be a hit or miss thing because my mobo manufacturer said that it should have worked.

By the way does the computer run when you turn it on with this memory in it? If so then it is running at the PC100 of your system, else the system wouldn't start. Hope this helps.
 
S

Slithy Tove

As stated already it should work. However, if you are considering mixing two different types of memory you may be setting yourself up for grief. If you begin to experience random lockups and freezes or other "unstable" behavior it may be due to different types of memory not happy with each other and not cooperating with each other. This happened to me with two un-matched sticks. I could boot and run fine until the ram decided to take a hike. The fix was simple... I could pull either stick and never have another lockup.
 
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I had this problem last thanksgiving. As stated twice before, it is backwards compatable, but as for the issue of why it's reporting half the actual ram size.

I found adds for free pc133 and pc100 ram. I was like "cool, let's get the pc133!" The biggest problem, it only reported half the ram. As you said, it's a pc100 slot, and I'm willing to bet your stick has memory chips on both sides. I went back to the store and the guy pretty much said "Oh, you need single sided ram, here's a stick of pc100". And that worked...this is just personal experience. If you have a pc100 slot, getting pc133 isn't going to help it at all...and I don't remember personally ever seeing a double sided pc100 stick. That's just me though.
 
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I'll vouch for double sided PC100 Ram :) I'm running 512MB of it right now, I've only seen single sided ram on edo ram go figure, just my 2 cents.
 

Chum

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The stick I put in(with no others) is Kingston...# on package is KVR133X64C3/256...it is single sided...lower on package it says...256MB PC133 Dimm CL3...

I am more confused than ever now... SGtheArtist mentioned "registered Ram"...what in the heck is that...Is it different than SDram...I thought I was getting SDram.

Now I am forced to try using it "along with" my 2 64 double sided sticks...to acheive 256. Is it something that can be set in my BIOS to repair this misread...mobo is BF6(Abit).
 
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motherboard will use either ecc(registered) or non ecc, you don't need ecc, mostly for server applications and it's actually a little slower.

Only thing I notice is kingston recommended memory for that machine is all cl2, not cl3, but cl3 should work.

Try it in a different slot

No bios settings that will make it recognize the memory that I know off.
 

Chum

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Called Kingston (wow, Toll free 24hr tech. support...talked with rep in less than 5 minutes)...he said for my mobo to recognize it as 256 it has to have chips on both sides. Get this...they said they would exchange it, free of charge...even, if I bought it from 3rd party! Sounds too good to be true...!
 
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Another possibility is that your board might not support a stick of 256. What is the model of the board? How old is it? Do you have the manual for it to check for compatibility? As for the single or double sided, they are both available for pc 100 and I am even currently mixing them, it just depends on what the board supports.
 
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Sorry Chum,

I didn't mean to confuse you, that's great that Kingston is going to replace that for you.

I looked up your mobo and it has the Intel 440BX the same chipset as my old mobo has and all intel chipsets need low density RAM and I think you got a high density 256mb ram which is used in motherboards that support AMD processors.

The reason I say your's was high density is because it had 256mb on one side (that is alot to have on one side)

You said yourself that your two 64mb were double sided :)

Well anyway I'm glad that Kingston is going to fix that for you.

The RAM industry really needs to make things clearer to computer shoppers.




By the way here is a link to the specs of your board:

http://www.techspot.com/reviews/hardware/abit_bf6/bf6-2.shtml

It can support up to 768MB of RAM
 

Chum

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SG...no need to be sorry. The difference between low and high density is exactly what the rep at kingston talked about.

Thanks for the link...I already have a manual, though. But I will still check it out...it may have more.
 
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Err, I apologize for confus'n ya. I'm just going off my own personal mix ups. I have a question though then. On my old mobo, the double sided ram would only report half the ram. Went back to the store, and they gave me single sided ram, and it all worked. Is density or whatever not backwards compatable? Seems like it should be.
 
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I think the density thing has to do with the mobo chipset (Intel, Sis, VIA) density maybe backward compatible with chipsets for AMD processors (because the high density chips are specifically for chipsets that support AMD & I would think if it can support high density RAM it could support low density RAM), however I've always ran Intel processors so I'm not for sure.
 

Chum

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I received replacement "double sided" ram in 2 days! It worked like it was supposed to work!!!

(every one who worked there, that I spoke with, was extremely friendly, and showed concern about their products meeting expectations...great company!) :D :D :D
 
S

Slithy Tove

Good Deal !! I think it's quite appropriate to give a public "plug" to a company that has done a good job - I'm glad you did, and I will keep it in mind.
 
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