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ermel

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PC100 & PC133 sdram memory together??

My question is will a stick of pc100 sdram and a stick of pc133 sdram sodimm, both 256mb work out ok in a laptop??
I installed them and laptop seems to be working ok.
What are the shortcomings of this? is it ok?
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mbu10

well depends on  couple of things
firstly if a new stick of 100 it will probley be able to run at 133
if a slightly older stick it will be running at 100
so if you stick both in the pc will be forced to the lower speed  of the 100 memory

problems
well if your pc only takes or runs should i say at 133 this will cause to bomb every now an then.

  But normally will pick speed up directly from chips (ie 100 or 133 ) and cause entire memory system to run at 100 instead of 133
but in real terms your not talking a massive amount and unless doing some serious work (cad etc etc or games) this will not make too much diffrence
when the pc boots it may say what speed runnning at if 100 then it has slowed a bit  if says 133 then i has accepted that it can run at 133 anyway
martin
if you mix up your memmory, your risking possibale constant freezing in your OS. also check out your bios too, because your bios might have an option of memmory installed  100 or 133, this has to be set right but that can't happen with mixed memmory. on the whole not a great idea.

Tazzy
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Wow, pc100/133... seems ancient nowadays ;)  

Some of my systems that run a mix of pc100/133 have their ram speeds set solely by the Front Side Bus (FSB) speed settings in my BIOS.  On my P3-733MHz machine, this means all my ram runs at 133MHz, regardless of the memory stick's speed rating.  On my P3-500MHz, all my sticks run at 100MHz. again, regardless of the memory's actual rating.

Basically, if you have a 133MHz FSB, and pc100 memory, you're running your memory overclocked (potentially unstable, run something like MemTest86 to test its reliability).  If you have a 100MHz FSB, and pc133 memory, the memory is underclocked, and I have never heard of this being a problem.
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I had to get somebody some additional pc100. Compared to pc133 quite expensive, so a asked a few people.
All advised me not to use pc133 in on a MoBo requiring pc100. The early pc133 modules were backward compatible, but the current ones supposedly are not...?!

Like to see your responses..... did I pay too much?
On desktops, high-density RAM modules are a problem, because old motherboards don't have the additional address lines to handle them.  This is a more important issue than whether it is PC100 or PC133.  See this thread from AlbertaBeef: https://www.experts-exchange.com/questions/20815547/Types-of-RAM.html
It also depends on the laptop. Some laptops that need PC100 will not work with PC133, or will only work with certain brands of PC133. If you tell us which laptop you have, like make and model, we can find out what memory controller it has, and what speed it really wants, and can search for others' experiences.

My guess is you've got a 100MHz bus system and since the PC133 in it not works, it should keep working just fine for you.

(My laptop has a 100MHz and does NOT like PC133 parts. Upgrading the RAM was uncomfortably expensive.)
what can happen is what heppened to me....
worked fine for 5 or 6 months and then........LOST ALL MY WORK, messed up te laptop which had to be sent to compaq and they weren´t able to fix it.


DON´T DO IT !!!! trust me ! it might work now but just wait a few weeks or months.
ive had no probems mixing these 2 together but all post mentiond above are correct
and of couse it would depend mostly on the type of ram you get and the mfg
there wont be any shortcomings as such .... just that your 133 mhz memory will run at 100 mzh ... also just for confirmation if ur motherboard support 133 mhz .. everything will work fine for sure ....
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Thanks for the confirmation, Anton74.
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I Laptop is an IBM T20 and recommended ram is PC100 but it seems to be running well with the PC133 and PC100 ram together in there. Thanks to all....I divided points as best I could...........if laptop acts up I will inform all.