Please educate me on RDRAM!

[PowerMac4Ever]

Hi there. I've got a friend who purchased a Dell that uses the RDRAM. It came with 128MB. I have a couple of quick questions:

All four memory slots are filled in the Dell. In an RDRAM board, does each slot need to have something in it?

RDRAM has to be installed in pairs, correct?

How would I be able to tell if it uses PC600, PC700, or PC800?

I would appreciate answers to these questions. Anandtech is awesome and I know someone here knows the answers to my questions. Thanks!

 

[mechBgon]

Two of the slots might be filled with "placeholders" called CRIMMS. If so, take them out and replace them with RDRAM modules.

What model of Dell does your friend have? I'm sure I can rummage up the info you want, if I know which model to look at on Dell's site.

 

[PowerMac4Ever]

It's an 8100-series, about a year and a half old.

I didn't know that CRIMMS had to be in all of the empty slots. Makes sense, I guess. Thanks for you help!

 

[PowerMac4Ever]

Ok, let's assume he has 2 64MB RIMMS and 2 CRIMMS. Would it be possible to take 1 CRIMM out and put in a 128MB RIMM there? Or, would I have to get 2 64mb RIMMS? But yeah, I would have to find out if he has 2 64MB or 4 32MB.

 

[mechBgon]

Looks like it's going to need PC800, judging by the CPUs Dell outfitted it with (P4 at 1.3GHz to 2.0GHz). To double-check, I looked at Kingston's memory configurator and that's what they're offering.

 

[mechBgon]

The RIMMs do have to be in matching pairs. CRIMMs look very different from RIMMs, so if you see two mostly-blank circuit boards and two modules equipped with heatspreaders, then he's got two 64Mb RIMMs and two CRIMMs. I don't think RIMMs are commonly available in 32Mb and it would have been a real disservice to the customer to build it that way, so I'm guessing it's got a pair of 64's.

So your options are:

• Add two new RIMMs and get a result of 128Mb (existing) plus either 128Mb, 256Mb or 512Mb additional, for totals of 256, 384 or 768
• or toss the two 64's and install two new pairs of RIMMS, with a whole bunch of possible solutions up to 1Gb total.

384Mb is a good amount for many purposes, short of heavy Photoshop work or something.

 

[PowerMac4Ever]

Thanks for your help mech. I just checked pricewatch and saw that there are no 32MB RIMMS available, so I'm sure he's equipped with 2 64MB RIMMs. I now know what I'm doing now.