Different size RAM modules

[RVB]

I recently bought some RAM in order to increase from 4x 2GB (8GB) to 4x 4GB (16GB). I only really need about 10GB.

However, the seller only delivered 2x 4GB and is being a pain in the arse trying to get them to send the missing 2x 4GB.

Finding matched sets of compatible RAM is very difficult, the module specs:
2GB 2Rx8 PC3 10600U 9-10-B0 (original)
4GB 2Rx8 PC3 10600U 9-10-B0 (recently purchased)

I need the computer back in action very soon and have to choose between:

1. Use the 2x 4GB RAM which was sent to me (it works perfectly) but be a bit tight for RAM.
2. Put the original 4x 2GB back in and be a bit tight for RAM.
3. Use the 2x 4GB RAM plus 2x 2GB RAM, give me 12GB of mixed RAM which will be plenty.

I'm tempted by option 3.
What do you think?

[essayer]

Mixed will be fine

[deckster]

Option 3 will be absolutely fine.

Although I'd be tempted to send the 2x4GB back, get a refund, and then buy from somebody else who isn't an arse.

[RVB]

deckster said:

Option 3 will be absolutely fine.

Although I'd be tempted to send the 2x4GB back, get a refund, and then buy from somebody else who isn't an arse.

Yes, it is tempting to tell them to shove it where the sun doesn't shine but most sellers only state RAM capacity, not all the spec numbers and part number. I can't just fit any 4GB modules because past experience says many of them won't work.

Unfortunately few, if any places seem to currently have 4GB 2Rx8 10600U 9-10-B0, let alone in multiples/matched pairs.

And in my experience, most computer parts sellers are cowboys.

[mmm-five]

Is this for an old Mac?

If so, and you're not after the cheapest 'refurbished' RAM you can find on ebay, then Crucial have the 2x4GB kits for £52 each ( via Amazon ) - unless this is the seller who's not delivering

Just checked my old 'spares box' to see if I have any from my old machines when I've upgraded - but there's only a single 2GB OE Samsung PC3-12800 CL11 1600MHz stick left

Edited by mmm-five on Friday 22 October 11:41

[xeny]

essayer said:

Mixed will be fine

This, ideally with a 2 and a 4 on each channel so it runs in dual channel mode, although it's often not a huge difference.

[mmm-five]

xeny said:

This, ideally with a 2 and a 4 on each channel so it runs in dual channel mode, although it's often not a huge difference.

If it's an old Mac, then I think it requires matched pairs of sticks...so won't run (or maybe just not recognise) additional RAM in a single slot.

[RVB]

It's a Dell.

It has four numbered slots in two pairs.

1, white clips.
3, black clips.

2, white clips.
4, black clips.

My understanding is that:
a) if RAM modules are identical, slots should be filled in the order 1, 3, 2, 4.
b) if RAM is two different pairs, it should have the white clips 1&2 with one pair (4GB modules) and the black clips 3&4 with the other pair (2GB modules).

[RVB]

And finally the seller delivered the missing RAM.
However, one of the two modules which arrived today doesn't work (process of elimination).

So I now have extra options because I have 3x 4GB plus the 4x 2GB originally in the computer.

1. Use the 2x 4GB RAM which was sent to me (it works perfectly) but be a bit tight for RAM.
2. Put the original 4x 2GB back in and be a bit tight for RAM.
3. Use the 2x 4GB RAM plus 2x 2GB RAM, giving me 12GB of mixed RAM which will be plenty.
4. Fit 3x 4GB and leave slot 4 empty, giving me 12GB total.
5. Fit 3x 4GB and fill slot 4 with 2GB, giving me 14GB total.

[mmm-five]

Don't know if the Dell demands slots filled in pairs or not, so why not simply put the 3 x 4GB sticks in and try it?

If it works, you know you've got an okay fall-back position!

Then try adding in the extra 2GB stick whilst you wait for a replacement of the faulty 4GB stick. If it doesn't work, simply go back to the 12GB position.

[Chozza]

What Dell ?

4 would be ok but i'd try 5

its only memory so ram it in :-) , and see.

[Griffith4ever]

I just upgraded the Ram on my Gigabyte Mobo and it was quite specific that the ram is installed in even numbers.

I went from 4,4,4,4 to 4,8,4,8 with the 8's being new. Same speed and spec, different brands etc.

PC had a massive strop and went on an endless boot loop at 1st

I installed 4,8,4,8 (colour matching sockets i.e. blue, white, blue white.)

Tried -,8,-,8

Same problem

Then I installed 8,-,8,- and it was happy!

Then I want 8,4,8,4 and it went back to previous behaviour.

In the end I discovered I wasn't seating the 2nd module (4) fully, It looked right, the clips on the side looked right, but it just need a bit more.

Just a thought.

[xeny]

RVB said:

b) if RAM is two different pairs, it should have the white clips 1&2 with one pair (4GB modules) and the black clips 3&4 with the other pair (2GB modules).

That matches my understanding. If you want to be certain, you can use https://www.intel.com/content/www/us/en/developer/... to check memory bandwidth as you change the config.