RAM

[RVB]

Recently I've been improving some old computers with SSDs and more RAM.

Today I was fiddling with a couple of computers - Optiplex 780 Q8300 and Optiplex 780 E6300 - to add more RAM.

After some experimenting, both computers were happy with RAM of the following specs:

Kingston 4GB PC3 12800U 11-11-B1
Hynix 4GB PC3 12800U 11-11-B1
Kingston 2GB PC3 10600U 9-10-B0
Hynix 2GB PC3 10600U 9-10-A0


But both were not happy with the RAM below:

Kingston 4GB PC3 12800U 11-12-A1
Micron/Crucial 4GB PC3 12800U 11-11-A1

The only differences are the last four digits.

Can someone suggest why the computers don't like 11-12-A1 and 11-11-A1 RAM?

Thanks!
R

[S6PNJ]

Without finding the actual models and looking the specs up, is one sort ECC and the other non-ECC by any chance? ECC is Error Checking and Correction (I think).

[RVB]

S6PNJ said:

Without finding the actual models and looking the specs up, is one sort ECC and the other non-ECC by any chance? ECC is Error Checking and Correction (I think).

No, I don't think so.
The labelling doesn't hint at it and I don't think there are any differences in the number and location of chips on the RAM.

[The_Jackal]

Mixing RAM is a crap shoot. There will be a reason for those different letters at the end.
You just have to ask yourself is it worth spending time bothering with it for old PCs.

But it will be something to do with memory timings.

Edited by The_Jackal on Sunday 2nd May 17:32

[RVB]

The_Jackal said:

Mixing RAM is a crap shoot. There will be a reason for those different letters at the end.
You just have to ask yourself is it worth spending time bothering with it for old PCs.

But it will be something to do with memory timings.

Edited by The_Jackal on Sunday 2nd May 17:32

I am not planning on mixing RAM.
I am fitting in matched pairs for the E6300 (only has two slots) or matched fours for the Q8300 if I have four of that type.

Whether the RAM is matched or not, those suffixed A0, B0 and B1 always work in either computer even if mixed up, and those suffixed A1 never work in either computer whether with identical A1 or with A0, B0 or B1.

And if I want to add more RAM, I need to know which is suitable, and more importantly, why it is or isn't suitable.
It's not easy trying to find 10yr old RAM with identical specs, especially in fours, so I will have to fit different but compatible RAM if I want to increase their RAM.

Understanding why the A1 RAM doesn't work would help a great deal in finding suitable RAM.
These computers are getting on a bit, but they are capable of many more years of service rather than just throw them away.

Edited by RVB on Sunday 2nd May 17:45

[speedyman]

It could be revisions of components on the board. Manufacturers need a way of identification when they update PCBs and test what works with what. As you have found out.

[robbieduncan]

For the Kingston at least the 12-A1 is single rank and the 11-B1 is dual rank