RDRAM installing question

[dbal]

I have already ordered my new system's configuration at my local retailer and while talking about the amount of RDRAM to install I concluded in 128MB for starters due to my depressed....wallet at this time.
Question is he told me he would install -when the components are all available- 1 stick of 128MB and I ask what about the fact that RDRAM is to be installed in pair of RIMMs to get the famous dual channels that provide the well-known super memory bandwidth?? Or the whole thing is totally irrelevant? Would it be installing 2x64MB sticks the proper configuration in order to get the awaited performance??
Thanx to all!!

 

[eplebnista]

Here is a link to AT's Rambus FAQ page.

hth,
eplebnista

 

[Saltin]

Generally yes, it needs to be installed in pairs, at least for the i850 chipset found in socket 478 P4 mobo's.
The thing is, you shouldnt just get 128 megs of it. You are going to want 2x128mb as a minimum. Also, make sure that the CRIMM's (Continuity RIMMS) are installed in the two slots not holding RAM. CRIMM"s generally come with any Mobo that uses this configuration.
Trust me on the amount of RAM. If you are building a p4 system with RDRAM, don't cheap out with only 128 mb. You will be sorry, and it will affect the performance.
If you want to go big, go all the way.

 

[dbal]

<< Generally yes, it needs to be installed in pairs, at least for the i850 chipset found in socket 478 P4 mobo's. >>



It's clear that I will need 128MB more soon in terms of performance (more RAM, double peak bandwidth due to the dual RDRAM channel of the i850). Since it's the first thing I 'll do the only question remaining is: Will the system boot normally if only a 128MB stick is installed?
I mean is it required to be installed in pairs or simply highly recommended regarding the undoubted performance boost?

 

[HappyPuppy]

From the link above:

"The i840 and i850 chipsets feature a dual channel RDRAM implementation that requires RDRAM to be installed in matching pairs, resulting in bandwidth of 3.2GB/s for PC800 RDRAM"

 

[shathal]

It is REQUIRED to have the memory installed in pairs.

It is equally REQUIRED that you put CRIMMs in memory-slots that are not filled with RIMMs.

Just trying to stuff a SINGLE RIMM into the board won't do it - you have to have BOTH running.

(Think of it like trying to drive a 4-wheel drive car with just the left or right set of tyres instead of all 4 of them). SDRAM boards (desktop ones) are usually single-channel, but have 4 slots (don't get slots & memory channels confused).

Think of it this way: SDRAM is mostly a SINGLE-LANE road, it just happens to be very long (up to 4 DIMMs). RDRAM on 850 and 840 is dual-channel, ergo DOUBLE-LANE. You MUST have a RIMM module in the FIRST element of each memory channel, otherwise the board will not boot.

Hope this answers your question well enough .