Can I use two different capacity DIMMs?

Danja

New Member
I would like to upgrade the RAM on my girlfriends' parents' computer. They currently have 256 MB and their computer uses a 240 MB page file just when idling on the desktop. I used crucial's memory scanner and it gave me several types of memory, including variations that came in 256, 512, and 1 GB capacity. I don't think that they would ever need 1 GB for the tasks that they do; however, 512 would probably be good. I've heard though that mixing different capacity RAM can cause stability issues in programs. Is this true?
 
Some system information as to make and model of prebuild or board for a custom case would help. The specifications will show what memory can be used.

As far as using different sized dimms between two channels it is best to see equal sized dimms while adding let's say a 512 on a channel seeing a 1gb dimm with the same on the second channel simply totals 2.5gb. With XP and a board that takes upto 2gb you would see Windows itself run better. Plus memory has come down quite a bit pricewise.
 
It's an old dell inspiron... I believe 4600. According to crucial.com,

Maximum Memory Capacity: 2048MB
Currently Installed Memory: 256MB
Available Memory Slots: 1
Number of Banks: 2
Dual Channel Support: No
CPU Manufacturer: GenuineIntel
CPU Family: Intel(R) Pentium(R) 4 CPU 2.80GHz Model 2, Stepping 9
CPU Speed: 2791 MHz

Each memory slot can hold DDR PC2700,DDR PC3200 with a maximum of 1GB per slot.*



I don't understand what you're saying in the rest of your post though. 512 + 1 gb = 1.5 gb, not 2.5, right? Why is it best to use equal sized DIMMs? Is there some kind of evidence for this or is it conventional wisdom?

Thanks.
 
Mixing DIMM sizes should be fine, if there are issues switch the slots, I had an old HP that didn't like it if you put a bigger DIMM in the 2nd slot but was fine if it was in there first. On the off chance that there are still issues, take out the 256MB, even with just 512MB they would be better off.
 
I haven't actually seen any significant evidence to vouch for this, but apparently, having matched DIMM's means that access rates are slightly better. In my desktop, I have 4 x 2gb slots in DDR2, but my laptop (new one) has 1 x 2gb and a 1 x 1gb stick. I don't notice the difference between a 1 x 2gb and a 2 x 512mb using the same processor and all other crap the same.
 
If you have two different DIMM's, where one is low latency and the other is your average value-RAM, then yes, all sticks will operate at the same speed and specs.
 
Most often when mixing different sized dimms of the same type the first slots sees the larger. That was typical with the older single channel boards. A pair of 512s or even better a pair of 1gb dimms to replace the 256mb stock dimm would see the system run far better.

The memory speed for the older system there will depend on the model cpu as far as the front side bus or fsb. For a slower cpu you would run PC2700 or run PC3200 seeing that run at the 333mhz speed of PC2700 memory. The closest match for a 4600 model desktop is a Dimention not Inspiron showing a 4gb capacity at http://support.dell.com/support/edocs/systems/dim4600/bp/4600i/sm/specs.htm
 
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