P4B533 vs DDR Ram 400 MHz

Charles Swiger cswiger at mac.com
Sat Jun 4 16:57:58 GMT 2005

On Jun 4, 2005, at 12:42 AM, Supote Lee wrote:
>   What if I using both of them together ? I mean using both
> DDR-266 and DDR-400 at the same time. Can I ?

Yes, if you make sure that both DIMMs accept the same voltage range.

The memory should work at DDR-266 speeds, but you may need to back  
off the memory timings (ie, go to CAS-3) for the system to be  
stable.  For example, I have one system which was using a 512MB  
PC2700 (DDR-266?) DIMM, and I added a 1GB PC3500 DIMM.  It would work  
fine at PC2100 (DDR-233), and almost work fine at PC2700-- but would  
generate a memtest error every few hours.

"almost" stable isn't good enough.  Since the system ran faster using  
just the 1GB stick at full speed, rather than trying to combine both,  
I've moved the 512MB stick elsewhere.

If you do combine memory of different speeds, be sure to test the  
combination out overnight using memtest or some similar utility.


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