HP 15s (AMD Ryzen 4000 series) memory issues

[SkyHound0202]

So I purchased an HP 15s-eq1125nw Laptop in Poland, which should include 8 GB DDR4-2666 MHz RAM memory in dual channel configuration (2 × 4 GB module). Since the processor, the AMD Ryzen 5 4500U, natively supports 3200 MHz memory, I thought that the laptop was limited by the max speed of the module (2666 MHz).

However, on the device I received, I was surprised to discover that it actually came with a single 8 GB DDR4-3200 MHz module (part number: 4ATF1G64HZ-3G2E2), rather than the advertised two 4 GB DDR4-2666 MHz modules. Essentially, this downgrades the dual channel memory configuration to a single channel one, losing 50% of the advertised bandwidth, which is particularly devastating to Ryzen processors and their integrated Vega graphics since they rely heavily on the wider memory provided by the dual channel memory configuration.

Furthermore, and perhaps more troubling, even with a 3200 MHz module factory-installed and the processor natively supporting 3200 MHz module, the system still runs at 2666 MHz. The memory speed setting cannot be modified in BIOS. This means not only I lost half of the available memory bandwidth, but I cannot even make up the loss in bandwidth through higher memory speed.

These findings present a few unanswered questions:

a) why I received a different, inferior configuration compared to the manufacturer-listed specification?

b) why the system refuses to run at a higher memory speed and disallow changes to be made in BIOS, even though both memory modules and the processor supports a higher memory speed?

While I can certainly pay with my own fund to purchase a compatible module to set up a dual channel configuration, the inability to run the memory at a higher speed just because of a missing BIOS/firmware feature is certainly a tough pill to swallow.

I hope both of problems can be addressed, first one through exchanging the single module for two modules (or alternatively provide an opportunity to purchase an identical module) and latter one through a BIOS update to unlock the memory speed selection (or just allow the memory to run faster).

[Huffer]

The motherboard cannot run the memory faster than -2666. That is how the system is advertised, as DDR4-2666:

HP Laptop 15s-eq1125nw Product Specifications | HP® Customer Support

And it may seem that dual channel vs. single channel results in twice the memory bandwidth, that is just not true in operation:

RAM Performance Benchmark: Single-Channel vs. Dual-Channel - Does It Matter? | GamersNexus - Gaming ...

The Service Manual makes it clear that the DDR4-3200 modules "bridge" to -2666 speed. 

Manual 

If you make a warranty claim you might successfully argue for getting a pair of 4 gb modules to replace your single 8 gig module. However, they (HP) will likely make you send it in to do that. Much easier to just add a second 8 gb module of DDR4-3200 SO-DIMM to have 16 total in dual channel. Under no circumstances are you going to get a BIOS upgrade to allow 3200 speed. If you have a way to return the laptop and maybe have a chance to fully research your purchase in advance you will be a happier consumer. Good luck to you. 

[SkyHound0202]

Thank you for your response.

I've read the article regarding single/dual channel memory performance you linked in your reply. It's worth mentioning that while most of the findings presented in the article were true, it was based on testing done on an Intel Core microarchitecture powered machine, which has a drastically different memory hierarchy compared to AMD Zen microarchitecture and is less sensitive on memory bandwidth. In addition, no information regrading the integrated graphics is available, which is also dependent on the memory bandwidth share with CPU cores.

I would challenge your statement by pointing you to this article by the same author on the same site, which shows single channel memory impacting the performance of an earlier AMD Zen/Vega-based APU. The problem persists in 4000 series APU found on my laptop.

Regarding the memory speed issue, I've read the service manual linked in your reply and discovered that the motherboard is exactly the same as the previous generation HP 15s (AMD) Laptop. The only difference between the current and previous generation is the processor (all Ryzen Mobile APUs are pin-compatible but firmware-incompatible) and the firmware. It maybe because the trace routing is not optimized for higher memory speed. You maybe right about not having a BIOS update for higher memory speed in the future.

About the resolution: I have contacted with the store and they agreed on a considerable discount for a replacement memory module. The store told me that they were totally unaware of the product change made by HP and there's no way for them to know the exact configuration of the device being sold. They have also updated the listing for the same batch of laptops in stock to reflect the different-than-manufacture memory configuration.

[Huffer]

Seems as if its resolved as much as possible. Good luck.