Do RIMMs have to be installed in pairs?

[Pakman]

I haven't had much experience with RIMMs, but it is my understanding they have to be installed in pairs. And they also have to have CRIMMs in any unoccupied slots. Does anyone have a good link that explains this?

 

[Oda]

On the i850 you need to install them in pairs because the memory access architecture is such that there are 2 channels being read/written simultaneously. On the i820 you do not need to install in pairs (ie you can install 1 module if you want) but you can't leave slots empty because Rambus is serial.

Oda

 

[Oda]

Well a good page about the whole Rambus jazz would probably be Anand's look at "Camino" here

[EDIT] Double post...

 

[thorin]

The i850 Chipset interleaves memory to increase performance, which requires you to install two modules at a time. On motherboards based on other chipsets you don't have to install in pairs but do have to use CRIMM terminators.

Thorin

 

[Redwingsguy]

yes what thorin said, get a RIMM job in pairs or get a terminator

 

[shathal]

As an addendum to Oda's (rather good & correct) explanation on i820 and i850 - the following.

First: a few general thins.
* EVERY RIMM channel has to be populated with at least 1 RIMM.
* If a board has more than one memory channel, this does mean that you have to install RIMMs in matching pairs (i.e.: 2x 64 MB, PC800).
* You CAN mix RIMMs on the first half & the second half of the channel.
Example:
1-channel RIMM:

Slot 1 => 256 MB PC800
Slot 2 => 128 MB PC800

2-channel RIMM:

Slot 1+2 => 128 MB PC800
Slot 3+4 => 64 MB PC800

i820 has 1 (!) RIMM channel (that equates to 2 slots total). The i850 has 2 RIMM channels (interleaved) which equates to a total of 4 RIMM slots. Because it is dual-channel (think EDO memory), you HAVE to populate i850 in pairs of 2 (!).

Right - I hope that this clarifies any remaining questions . If you need more info PM me or something .

 

[Pakman]

Cool... thanx for all the info... So I guess if you have a Pentium 4 then you have to install them in pairs since it uses the i850 chipset? Can you mix and match different speeds like say 600mhz and 800mhz Rdram?

 

[Jumpem]

they must be the same speed or the PC800 would run like PC600 I think. If you're getting a P4 definitely use PC800, as there is a definite performance drop using PC600.