Last week my friend's Dell Latitude died after a power outage. I didn't manage to get it running again, but using an adapter, I read out and copy his documents from his hard drive. That made him so happy that he gave me the Latitude, and I butchered it looking for parts. In addition to a 120Gb SATA drive and a T2400 Dual Core CPU for my T60, I found two 512MB PC2 4200 RAM modules. Can I use these in my T30?

I know the RAM modules are to some extent backwards compatible, and will run at lower speed. But the T30 has PC2 2100 modules, which I believe run at 266MHz, while these are 4200/533MHz modules. Or can this be a DDR vs. DDR2 issue? I know the T30 use DDR, but I am not sure where the DDR2 range starts.

Thanks!

You can not use them, as far as I know, they wont even fit.

Ron

DDR2 modules can be identified by speed from the label. PC2-xxxx, denotes DDR2, while the older DDR sticks are just PC-xxxx. You can also usually tell the difference between DDR and DDR2 as anything at 4200 or over is DDR2; 2700 and below is DDR. There is one speed where you need to be careful and that's 3200. Both DDR and DDR2 were made at that speed (effectively a 400Mhz data rate).

As long as you stay within the DDR or DDR2 framework, faster rated modules will generally run at lower speeds but you also have to watch out for some other timing parameters. CAS latency or CL is one of them.

DDR and DDR2 modules cannot be inserted (easily ) into the other socket. There's a "key" or notch along the edge of the module which is supposed to prevent accidentally putting the wrong type in the system.

Ah, ok. So the DDR2 generation starts at 4200, and the PC2 prefix relates directly to DDR2. Good to know. I also see that I did a typo, the T30 uses PC-2100, and not PC2-2100.

(I should have known this, as I somewhere deep in the back of my mind know that T43 4200 RAM isn't compatible with RAM from earlier T4Xs, due to DDR vs. DDR2 incompatibility )

So that's it for my plan for expanding the T30 RAM with free modules. Guess I have to search for some PC-2100 or PC-2700 modules when I get back to the US.

rkawakami: Thanks for the explanation!

Ok, a quick question as a follower up to my previous RAM question:

I bought an used 512MB SODIMM from a user here, and installed it this weekend, in addition to the existing 512MB module. But the OS only saw my existing 512MB. So I took the existing one out, and tried the "new" module in both slots. With this module in slot 1, I got the 1-3-3-1 beeps (Slot closest to the front) while the module in the other slot just gave a black screen, no beep, no boot, no nothing. The existing and working 512MB module works from both slots.

So can I inform the seller that his module was bad, or is this more complicated? Can a failing memory slot cause it to only recognize certain types of modules? Just making sure that I am not accusing anyone of selling me a bad RAM module here.

Thanks!

Without knowing exactly what the "new" module is, I can guess and say:

- the "new" module may be defective or incompatible with your system
- the front memory slot may have the infamous loose connection(s)

That your existing 512MB module works in the front slot may simply just be luck. There may be enough pressure/stress for the slot connection to be properly maintained. You could try putting in your "new" 512MB module in the front slot (leave the rear open) and wedge a thick piece of paper between the module and memory cover. If you get the same no screen, no beep, no boot condition that occurs when that module is in the rear slot, then that would say the module is the problem. Assuming that you are dealing with a slot problem, I suppose it could be possible that the front slot does not "see" certain modules. It really depends on which pin(s) are being affected.

What is the exact model number of the "new" module? And if visible, what's the markings on the individual memory chips on that module?

Actually, the earliest DDR2 RAM was PC2-3200. Also, the last DDR RAM was PC3200. So, DDR and DDR2 overlapped at 3200.

Ok, I have done a couple of more tests.

With a piece of thin bubble wrap between the cover and the slots/modules, the result is the same no matter which slot I install the "new" module in. Fan spins, system is on, but black screen and no boot. This happens no matter if the RAM slot cover with the bubble wrap is present or not. So I guess yesterday's scenario with the 1-3-3-1 beeps was probably just a result of me not seating the module properly. The old module still works from both slots.

The sticker on the "new" Micron module says:
MT16VDDF6464HG-335C2
PC2700-2533-1-Z
512MB DDR, 333, CL2.5

The individual IC chips are all marked:

4GC22
D9BJV

This seems to be a DDR PC2700 333MHz module, like I am supposed to have. My knowledge is not extensive enough to say anything about the CL value, though.

(Ok, so the Micron module says: "Country of origin Singapore." So much for supporting local business. We have a Micron manufacturing plant here in Boise)

My best guess would be that your "new" DIMM is defective. If it won't boot in either slot which were proven working by another piece of RAM, you may want to return it...

My $0.02 only...

Last update, and end of story:

Since the seller is among the group of honest people here on the forum, he sent me a different module. This module was installed and worked just fine in my T30, so the problem is solved for me.

Upon request from the seller, I mailed the non working module back to him today, so we will see if the module works for him. I have no other system around right now that takes DDR RAM, so I had no chance to test it in any other machine than the T30. He was very surprised that the module didn't work, and he was pretty sure it was tested before he sent it. That's why I chose to put all this work into testing it before deeming it defective.

I got a memory module that seemed to be defective. I looked carefully and noticed that a label extended just onto the gold connectors. I removed the label and it worked fine. I think the label was put on by the reseller. Anybody adding labels to memory modules, watch what you are doing!!