Mixing 2 memory with different speed

[andiekurniawan]

Hi All,

What would happen if we combine 2 memory with different speed?

I have an Acer laptop with 512 MB DDR SDRAM at 266MHz. I want to
upgrade my laptop memory to about 1.5 - 2 GB. It has 2 memory slots.

However, it seems that memory at 266MHz has been discontinued from
production.

What would be the best way for me?

2 alternatives that I can think of are:

1. Buy 1 GB DDR SDRAM at different speed and combine it with the
original 512 MB memory.
Pro: this is the cheapest option
Cons: it might not work or the speed might be cut down to 266 MHz

2. Throw away the 512 MB and replace it with two 1 GB DDR SDRAM / 2 GB
DDR SDRAM with higher speed.
Pro: fast?
Cons: is that possible to replace the 266MHz memory with higher
speed? Would it still work? Expensive.

Thanks.

 

[Marcel Overweel]

It's not advised to mix different brands/speeds.
Some say that both memory modules will run at a speed equal to the lowest
memory module.
Others say when timing is different between two modules, it can get very
unstable.
Manually setting the memory timings in bios might be required.

I've tried it once with all bios settings on auto and it didn't work.
First it looked allright but after stress-testing it with memtest86, random
errors appeared.
I was just curious if it should work right out of the box and I didn't
bother trying to change the
bios settings though.

Even using two modules of the same speed and brand can give problems when
you try
to use them in dual-channel mode (if your mobo supports that?).
In that case it's best to buy a dual-channel kit which means two memory
modules of the same
brand, same speed AND same production batch (or tested for dual channel
compatibility).

As for speed, as far as I know, the modules will run at the hightest
possible speed your
mobo supports.

Whatever you do, make sure your reseller can give you other memory modules
to try if the
first won't work and you can get your money back if all seems hopeless.
And don't forget to test it with memtest86 or other memory test program.
(http://www.memtest86.com/)

Hope this helps,
Marcel

 

[andiekurniawan]

Marcle,

Great answer and quick reply too.

Heap thanks for your help.

I'll ask my reseller tomorrow.

Regards,
Andie

 

[Michael Hawes]

It's not advised to mix different brands/speeds.
Some say that both memory modules will run at a speed equal to the lowest
memory module.
Others say when timing is different between two modules, it can get very
unstable.
Manually setting the memory timings in bios might be required.

I've tried it once with all bios settings on auto and it didn't work.
First it looked allright but after stress-testing it with memtest86,
random
errors appeared.
I was just curious if it should work right out of the box and I didn't
bother trying to change the
bios settings though.

Even using two modules of the same speed and brand can give problems when
you try
to use them in dual-channel mode (if your mobo supports that?).
In that case it's best to buy a dual-channel kit which means two memory
modules of the same
brand, same speed AND same production batch (or tested for dual channel
compatibility).

As for speed, as far as I know, the modules will run at the hightest
possible speed your
mobo supports.

Whatever you do, make sure your reseller can give you other memory modules
to try if the
first won't work and you can get your money back if all seems hopeless.
And don't forget to test it with memtest86 or other memory test program.
(http://www.memtest86.com/)

Hope this helps,
Marcel

Go to Crucial or Kingston site and use product adviser. i think they
guarantee to replace/refund if problems.
Mike.