Help - memory and clock speeds

  Tony Spear 03:35 08 May 2004

MY memory is failing! I can't remember if SDRAM is backwards compatible i.e. can my mate use PC100 or PC133 modules in his computer with a 66MHz. FSB speed?

Similarly can I use PC133 modules with my 100MHz clock speed?

  Tony Spear 03:43 08 May 2004

What's the difference between ECC and non-ECC RAM?

Are they compatible with each other, or does every module installed have to be the same?

  Tony Spear 13:56 09 May 2004

Not one reply yet!

  ste_bla 14:01 09 May 2004

EEC is to do with memory correcting code or something like that most pcs dont use it as its more expensive and there arnt many errors anyway!

Not sure about clock speed best thing to do is check your motherboard specs..

  Tony Spear 15:54 09 May 2004

Thanks for this, although it doesn't help very much. I've been offered a fairly large chunk of cheap ECC RAM (it's probably cheap for the very reason you mention), but I can't figure out whether it will work in my computer alongside the existing non - ECC RAM!

As far as the clock speeds are concerned all my motherboard manual tells me is that my clock speed is 100MHz, but it doesn't tell me if PC133 RAM will work in it!

Any advice greatly appreciated.

  ste_bla 16:04 09 May 2004

what mobo you got and i meant non-ecc is norm cheaper and commonly used and is also faster as no error code checking..

also you will find try and use the same sorts of ram in a system as it works better

  cream. 16:07 09 May 2004

Yes you can use pc133 ram in a motherboard that only takes pc100. So it is backwards compatible. It will automatically run at 100Mhz. Thats the good news.

It would be very unlikely that non-ecc ram would co-exist with ecc ram. You would most likely encounter a lot of BSOD. ECC ram is most used in servers where it is critical to get things right.

If the ram is "a fairly large chunk of cheap ECC RAM " You could take out your exsisting ram and just put in the ecc ram. It will drop down to 100Mhz ( pc100)

Also take into account that pc133 and pc100 ram is very expensive to buy new at the moment. click here
So if it is a hefty module going cheap, then it may be worth grabbing.
Hope that gives you a bit more information.

  Tony Spear 18:59 09 May 2004

512MB for £30!

But (there's always a but)!

My MOBO manual says it takes un-buffer SDRAM - is this the same as non-ECC?

Also it's described as "registered" - what does that mean?

  cream. 20:19 09 May 2004

Could you post your motherboard details, as you have the manual.

ECC ram comes in both sorts, buffered and unbuffered click here

I would think the odds are that the ECC ram is buffered and without knowing the exact motherboard it is difficult to advise. Also can you supply the code numbers on the ram chip?

For your reference,


"Buffered modules contain a buffer to help the chipset cope with the large electrical load required for large amounts of memory. The buffer electrically isolates the memory from the controller to minimize the load that the chipset sees. However, unbuffered modules are the most common. In unbuffered memory, the chipset controller deals directly with the memory. There is nothing between the chipset and the memory as they communicate. Registered modules are unbuffered modules containing a register which delays all information transferred to the module by one clock cycle. This is usually done on modules with a large amount of memory to help ensure that the data is properly handled. The design of the computer's memory controller dictates which type of RAM must be used and buffered and unbuffered RAM cannot be mixed. Most buffered and registered modules also have ECC and are used in high-performance systems, where it is extremely important that the data is properly handled."

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