The Last RAM Question

[Big Al]

The RAM that came with the computer is PC 66 with a bus speed of 66 MHz. The RAM I bought is PC 100 which I understand will work fine on a 66 MHz bus. My question is can I mix the PC 100 with the PC 66?

Big Al

[Reid]

I have mixed memory speeds with no problem, but of course the memory bus speed needs to be set for the slowest module.

Crucial's FAQ (http://support.crucial.com/scripts/crucial.exe/search) says:

"In general, you CAN mix different speeds of SDRAM memory in the same system. The faster memory will run at the slower memory's speed. However, there are some systems that will not correctly run this memory configuration. This is rare, but we suggest you contact your computer manufacturer or motherboard manual to be sure."




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reido@my-deja.com

Friends don't let friends install Windows ME

[Rick]

Also Make sure you install the slower ram in the first two memory slots.
that is where your bios will look for the speed if you have autodetect enabled.

[sleddog]

I've often seen it said that, when mixing RAM of different speeds, the RAM will run at the speed of the slower (slowest) module. This is only partly true. Good motherboards usually let you set the RAM speed: either the same as the FSB, or to the FSB +/- the system bus. For example if your FSB is at 100MHz, you can choose to set the RAM to 100MHz or 133MHz.

If you have PC100 RAM and you set it to 133MHz you are overclocking it. Whether it works or not depends on the quality of the RAM. High-quality PC100 RAM can easily run at 133MHz (or more). Low-quality RAM won't be able to do it. Nothing terribile will happen -- the machine simply won't boot correctly, or will crash when attempting to load Windows.

If you have, for example, a mix of PC100 and PC133 RAM, it will all run just fine at 100MHz. There's a fair-to-good chance it will also run at 133MHz, which you won't know until you've tried it. Again, this is a form of overclocking and I don't mean to advocate it here. But I wanted to set the set the record straight.

(Personally I have two different PC100 RAM modules: one 64mb single-sided, one 32mb double-sided. They've been running happily for months at 148MHz -- that's the luck of the draw http://www.PCGuide.com/ubb/smile.gif




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sleddog
[sleddog.f2s.com] (http://www.sleddog.f2s.com)

[FatArgyle]

Could someone please clarify this for me? I have read several different opinions on this...

I have a P-2 Celeron (eMachines) with a 66-Mhz front-side bus. Right now I am running on a measly 32 MB RAM, and want to buy some more. My question is, can I install PC100 RAM without any danger of incompatabilities or instability? From what I understand, this will work fine, and the PC100 actually seems to be cheaper.

Thanks

[Paleo Pete]

In most cases the PC-100 will work fine. On some older systems, like my P-233MMX it might not, for reasons I can't explain. Maybe someone else can. I don't fully understand the differences in memory yet...About all it will do is run the PC-100 at 66MHz instead of 100MHz, assuming your system bus is 66MHz. You most likely won't notice a major difference in performance, the performance increase you do notice will be more from having more RAM than from the bus speed.

Mixing 66MHz and PC-100 will usually work, same result, it will run at 66MHz instead of 100.

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[kenja]

My recent experience mixing PC100 and PC133 on 66MHz motherboards: I've got a Celeron Presario that came with PC100 DIMMs. I've also got a 366i2 Celeron Emachine that came with a 32MB PC100 DIMM. Pulled the original memory out of both machines. Installed a 128MB PC100 DIMM in each machine; no problem. Installed a 128MB PC133 (for a total of 256MB) in the Presario; it wasn't recognized, even after swapping slots. Thought I might have to make use of Kingston ValueRam's lifetime warranty, but tried it in the Emachine first; no problem! Put two 128MB PC100 DIMMs in the Presario; no problem.

From the user forum for my Celeron Thinkpad: PC66 SODIMMs work (of course), and PC100 SODIMMs work, but a PC66 SODIMM and a PC100 SODIMM wont work together!

Moral of the story: It usually makes sense to buy faster-than-necessary memory (at the same price or less), with the idea of transferring it to an upgrade machine later on, but it doesn't always work out!

Note to FatArgyle: I've never seen any compatibility problems with the 32MB Samsung DIMM that came in my Emachine.

[FatArgyle]

Thanks for the info. The computer that I am upgrading is actually the 366i2, so it is reassuring to know that you have had no problems with it.

[mjc]

The thing is it Samsung branded RAM and not generic. Samsung is not exactly top of the line nor is it bottom but good mid quality and you shouldn't have any problems mixing it with any resonable quality RAM (sheesh! I sound like I should be writing ad copy for Samsung.... http://www.PCGuide.com/ubb/biggrin.gif )BTW, my so called PC66 stick of Samsung is actually PC100 (it came in an HP)

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mjc
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