Upgrade workstation memory non-pairwise

Question

I have a HP Z420 that has 4 DIMM's installed of 8GB PC3 14900E memory (8 slots total). I have an option to install one more 8GB DIMM but I was concerned that installing memory in a non-pairwise fashion would actually degrade performance due to the memory being dual channel. Does anyone know if this is the case?

Update: it's a HP Z420 workstation and the memory is dual channel

Define "workstation". The answer depends completely on the make and model of the computer (or of the motherboard, if this is a custom-built unit). — Massimo, Mar 15 '16 at 18:29
[System spec, HP Z420 Desktop Workstation](http://www8.hp.com/us/en/campaigns/workstations/z420.html). Memory (from HP): *8 DIMM slots; Up to 64 GB (8x8GB) ECC unbuffered DDR3-1866 (Transfer rates up to 1866 MT/s) (600W PSU chassis); Up to 32 GB (8x4GB) ECC unbuffered DDR3 1866 (Transfer rates up to MT/s) (400W PSU chassis); 4 channels per CPU* — user, Mar 15 '16 at 20:15

score 2 · Accepted Answer · answered Mar 15 '16 at 20:32

2

As per the official documentation of the workstation, usign five 8-GB modules for a total of 40 GB is not a supported configuration; also, none of the supported configurations uses five modules: there are either 4 or 6 of them.

However, it might work if you follow the correct loading order: fill slots 1, 8, 3 and 6, and then put your additional module in slot 2. If this doesn't work, then you'll need at least another 8-GB module to put in slot 7.

answered Mar 15 '16 at 20:32

Massimo

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Thanks. I had no idea that documentation to this detail existed – Alex Vallejo Mar 16 '16 at 00:40
Next time, try Google: it's literally the first result for "hp z420 ram" :) – Massimo Mar 16 '16 at 09:11

score 0 · Answer 2 · answered Mar 15 '16 at 18:22

0

Most workstation would be fine with non-paired, if the 8 GB size is supported. ECC memory is better installed in pairs and yours PC3-14900E is ECC.

Without particular model information of the workstation it is hard to devise if a non-identical RAM will work for your workstation.

You can post your workstation model information for relevant answers.

answered Mar 15 '16 at 18:22

I tried to install the extra stick but the system wouldn't boot. I don't know if maybe I need to modify something in the BIOS...? – Alex Vallejo Mar 15 '16 at 20:09

Upgrade workstation memory non-pairwise

2 Answers2