Memory Module MisMatch

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I have an HP Pavilion that uses 168 pin, 100Mhz, SDRAM.
If I add more RAM in the form of the same module except for 133Mhz will I be causing a problem or will it run OK but just at the slower speed?
100Mhz chips are running almost 1 1/2 times as much as 133Mhz modules!
Looking to add a 256 MB module…

As always! Thanks for the wealth of knowledge imparted from these forums!!!

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Presumably you already have an unused 256 MB, 133 MHz memory module, otherwise you wouldn’t be asking the question!

It is often best to get matching memory, particularly when running XP, because it is rather sensitive in this area. People often recommend Crucial memory, because their website is very helpful, and gives all the appearances of knowing what it is doing! But presumably your original memory is what HP found cheapest at the time it built your Pavilion? Using the same memory manufacturer now may be more expensive, but could be more reliable.

Theoretically a faster speed memory module ought to run successfully at a lower speed, so why not try it? It would be worth downloading, installing on a bootable floppy or bootable CD, and running, Microsoft’s Memory Diagnostic (peculiarly singular, I note). Also note there seem to be no absolute answers when it comes to memory .

Bona fortuna!

John

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I think I will start with the memory diagnostic and then work my way thru your suggestions. Yes, the present memory is factory installed with no markings on it.
Thank You for your very helpful reply!

F. Ed

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To add to John’s comments – “in theory” memory can always toggle down to a slower speed – as long as it physically fits in the slot.

In “practice” I have upgraded with 133 modules in 100 slots dozens of times with NO problems – so THIS time, theory seems right. The good thing about Crucial is that it tells you what type of memory your motherboard supports – you don’t have to buy crucial. Kingston offers a similar service.

Bill (AFE7Ret)
Freedom isn't free!

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This time theory did not support practice! This ‘Proprietary’ machine will only accept the same type AND speed!
Got the right module and it seems to have accepted it and is working fine … only cost me shipping three times and a $5.00 re-stock fee and $28.00 more for the chip because of low demand!

OH well Birthday is coming and I may give myself a present!!!

Thanks again Folks!!!

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When you say theory did not support practice, what do you mean? Did you physically install 133 in a 100 slot and it failed?

What I was saying was that if the system called for 100, you could install 133 modules and they would work fine – you would not see the increase in 33MHz because those modules would be throttled back to 100 – but should still work fine.

Bill (AFE7Ret)
Freedom isn't free!

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But you shouldn’t try to mix different speed memory modules, that is likely to lead to somewhat unpredictable behaviour.

StuartR

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I agree with Stuart – to a point. In older systems that take 100s – you can mix 100s with 133s with no problems. In systems that take 133s, you can put 100s in there, but you will have to toggle down your FSB.

On newer systems, especially those that support Dual Channel memory – then you can NOT mix up the modules – in fact, they often have to be bought in matched pairs.

Bill (AFE7Ret)
Freedom isn't free!

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