Mixing memory speeds?

[dieselzaf]

I have a laptop that uses pc2100 ram. I've been wanting to upgrade and the pc3200 ram is even cheaper. I know that since my mobo only supports 266mhz that it won't utilize the pc3200 to it's potential. My ? is will it work fine and downclock itself to run comapitably with the pc2100 ram currently installed. I only ask because the faster ram is cheaper. I know ddr2 and ddr can't be mixed, but what about speed??? Thanks.

 

[Cousin Patty]

I believe the CAS latencies have to be the same for them to work together. Otherwise they should be ok i THINK. someone feel free to correct me here.

 

[c0mfortably_numb]

I personally don't recomend mixing memory speeds, I would check out crucial and what ever they say works in that laptop get that.

 

[tkam]

It should work fine it'll just run at the same speed and latency settings as your slower RAM.

 

[dieselzaf]

The pc2100 latency is 2.5 while the pc3200 latency is 3.0, I hope that is ok. They both run at 2.5 volts, but the different latency scares me a little.

 

[brian183]

I'm too experienced with laptop BIOS but most allow you to change latency times for your memory. If your bios can do this then it would be a simple matter of changing 2.5 to 3.0. Chances are, your BIOS will automatically detect your memory parameters so I think you'll be ok.

 

[Torm]

Usually mixing memory works OK - you will however run at the speed of the slowest memory module. Typically your BIOS' memory config is set to "by SPD" which means the system will read the specs of the modules and adjust to that. However in some cases this can cause problems (some modules have incorrect specs) - and if it does then try setting your BIOS manually to the specs of the slowest modules in your system. By slowest i mean whatever module have the highest CAS latency number. This is typically designated in this fashion 2.5-3-3-7. Here 2.5 would be the CAS latency.

Another factor that can cause problems is if the modules requires significantly different voltages to run stable. I would be surprised if this would be a problem however as most modules can run stably at any voltage between 2.5 to 2.75V.

Finally some systems (i dont know specifically about laptops) experience stability issues when using more than 2 modules. Ideally one should try to avoid more than 2 modules. However this seems to mostly be an issue in very high speed / OCed systems.

 

[device manager]

Please keep in mind that some of the newer 16 chip BGA (SODIMM) memory modules have a compatibility issue with various systems. Since you have DDR266 I would recommend that you look for 8 chip TSOP memory.

 

[dieselzaf]

Thanks for all your replies, I will post the results as soon as I get the memory. If it works, I can't wait to see the difference going from 640mb to 1.5gb. (fingers crossed)

 

[JaGWiRE]

Run memtest86+ after you mix the ram, mixing ram is always a very bad idea from all my experiences though.

 

[Eagle_Driver]

I would not recommend using PC3200 memory in a laptop designed to use PC2100 memory -- because no laptop has any provision at all whatsoever to adjust any memory timings or speeds (in other words, they will always use the modules' SPD no matter what). What happens there is that the laptop's BIOS will not even recognize that there is an SPD at all on the PC3200 module (since all PC3200 SO-DIMM's have SPD programming only for PC3200 operation); thus, that PC2100 laptop will not even boot up at all (not even into the BIOS).

 

[dieselzaf]

This is interesting, I found this on crucial.com. How come it is ok to mix pc2700 ram with pc2100 then? Crucial doesn't carry pc2100 so they recommend pc2700 to be mixed in with my pc2100. Is mixing pc2100 with pc2700 different than pc2100 with pc3200???

 

[device manager]

Quote:

Originally Posted by dieselzaf Is mixing pc2100 with pc2700 different than pc2100 with pc3200???

No. However take note of my previous post and order the correct module.

 

[dieselzaf]

DM, thanks for the advice. I will find out if this is a 16 die chip, although it doesn't state it in the specs section. I've only seen 16 die chips so far for 184 pin desktop ram. Looking into it.

 

[device manager]