Clarification on HP Zbook 15 G4 allowable RAM speed

[jwhendy]

I'm looking at the manual for this laptop, found HERE. I see the following on pg 2:

"""

Support for DDR4 2133-MHz, dual channel memory

Support for DDR4 2400-MHz, single channel memory

Support for 64-GB of system RAM in the following configurations:

DDR4-2400 (for use in models with Core processors):

- 65536-MB total system memory (16384-MB×4)

- 32768-MB total system memory (16384-MB×2 or 8192-MB×4)

- 16384-MB total system memory (16384-MB×1, 8192-MB×2, or 4096-MB×4)

- 8192-MB total system memory (8192-MB×1, 4096-MB×2)

"""

My understanding is single channel means one would use one stick of some amount, while dual channel means multiple matched sticks.

I'm confused by the spec on support for 2400-MHz single channel, while then listing out combinations of only DDR4-2400 in matched sets. Wouldn't this mean that it also supports DDR4-2400 in dual channel mode? I just don't want to order 2x16G or 4x8G in 2400MHz to find out it can only use one of them or something.

Thanks for any clarification!

---

Edit: also, I thought 16x2 was dual-channel and 8x4 would be quad-channel. If that's correct, I would expect to see "quad-channel" listed above, or only 2x configurations in the list.

[banhien · Accepted solution]

@jwhendy

The following note may explain a bit more

       

Source:  http://www8.hp.com/h20195/v2/GetPDF.aspx/c05381086.pdf

Dual channel runs in pairs, with 4 sticks you have TWO pairs each runs dual channel. I have not heard RAM runs quad channel.

Regards.

[jwhendy]

@banhien

Super, super helpful. That does,  indeed, clear it up. So 2 chips is the best configuration from what I read; above 2 and you're reduced to 2133. And to do dual-channel, you need matched pairs in one or both of the double slots. Thanks for the quick response!