Frequent ubuntu "freezes" after RAM upgrade

[Steve]

On Sat, 26 Dec 2009 19:20:31 -0000, Andrea Fortino  
<andreas.fortino at gmail.com> wrote:

>
>> On Sat, 2009-12-26 at 19:55 +0100, Andrea Fortino wrote:
>>>  >> Hi,
>>> <SNIP>
>>>  >>
>>>  >> BIOS can read all of 3 GB, but ubuntu often "freezes" after some  
>>> minutes
>>>  >> of work. So I try ubuntu memory test (option from GRUB menu). Test  
>>> #5
>>>  >> ("block move, 64 moves") reports numerous errors. Retried memory  
>>> test,
>>>  >> with only 2 GB (checked every possible combination of 3 blocks): no
>>>  >> errors found.
>>> <SNIP>
>>>  >>
>>>  >> Ciao,
>>>  >> Andrea
>>>  >>
>
>
> accessys at smart.net ha scritto:
>>>> have you tried removing one of the card s and seeing how it ran with  
>>>> 2gb
>>>> rather than 3gb??
>>>>
>>>> Bob
>>>>
>
> Andrea Fortino wrote:
>>> Yes, thank you, now I'm running with 2x1GB, but I often use virtual
>>> machines so 3 GB would be much better.
>>>
>>> I thought maybe something wrong with one of the 3 RAM slot of the
>>> motherboard, but I checked all of them: they works. Problem should be
>>> software, but I can't find where.
>>>
>>> Andrea
>>>
>
> arshad ha scritto:
>> is it something to do with 32bit and 64bit?
>>
>
> I think 32 bit systems allow up to a total of 4 GB... hey, wait a
> minute: may be I should _resize_ swap partition (1GB instead of 1,5GB)??
> ..so total RAM would be 4GB (3GB RAM + 1 GB swap)!
>
> May be it could be the solution?
>
> Andrea
>
Swap doesn’t work like that. The 4GB limit is the amount of physical RAM  
that can be addressed.

As for your problem, it is to do with memory speed, believe it or not.   
The faster the memory the less it can address, for some reason.  From the  
manual of a MOBO of similar vintage:-

PC1600/PC2100 for 3 DDR DIMM slots, Max 3GB.
PC2700 for 2 DDR DIMM slots, Max 2GB.
PC3200 for 1 DDR DIMM slots, Max 1GB.



-- 
Steve