Intel Core Ultra 9 285K Linux Memory DDR5 Performance Testing

Following last week's launch testing of the Intel Core Ultra 9 285K and Core Ultra 5 245K Arrow Lake desktop processors, the next area I've been exploring deeper has been the DDR5 memory performance including with CUDIMMs. Here's a closer look at the Core Ultra 9 285K performance under Linux while testing several different sets of memory and running Ubuntu 24.10.

The most important takeaway I have since my launch-day testing of the Core Ultra 9 285K is that the ASUS ROG MAXIMUS Z890 HERO has been working out much better on the 0806 BIOS now available from the ASUS website. With the 0805 BIOS for the ASUS ROG MAXIMUS Z890 HERO I was still encountering some application hangs and segmentation faults particularly when using DDR5-8000 memory. But in my testing the past several days, the 0806 BIOS version is working out much more reliably with the assortment of DIMMs I've been testing. ASUS release notes for the 0806 BIOS notes better compatibility with high capacity DIMMs, updated Intel CPU microcode, and other changes.

One of the exciting features for Arrow Lake is having support for CUDIMMs for featuring a client clock driver (CKD) to re-drive the clock signal. The intent with CUDIMMs are to improve signal integrity and reduced noise and jitter. With the stronger signal integrity opens up the door for higher memory speeds. Various vendors have announced DDR5-9600 CUDIMM RAM and even teasing DDR5-10000 speeds but most of these high speed CUDIMMs will only be coming to the market later this year or in early 2025.

For what's available to buy right now, Crucial is already to market with their 32GB Kit (16GBx2) DDR5-6400 CUDIMMs. DDR5-6400 speeds aren't particularly exciting especially with a CAS latency of 52. In any event being curious to test out CUDIMM support with Intel Core Ultra Series 2, I ended up buying the 32GB kit (CT2K16G64C52CU5) for testing. The 32GB Crucial DDR5-6400 CUDIMM kit currently retails for $169 USD. Again though in the coming weeks/months should be much more interesting CUDIMM kits that will be far more interesting for testing.

For getting an idea of the Arrow Lake sweet spot for DDR5 memory performance and how the overall stability was, over the past several days I tested out a number of DDR5 memory kits I had on hand plus the newly purchased Crucial/Micron CUDIMMs. In this article are benchmarks of the Core Ultra 9 285K while using the following sets of DIMMs:

- 2 x 16GB DDR5-6000 Crucial CP16G60C36U5W.M8D1
- 2 x 16GB DDR5-6400 Micron CT16G64C52CU5.M8D1 CUDIMM
- 2 x 32GB DDR5-6400 Corsair CMK64GX5M2B6400C32
- 2 x 24GB DDR5-7000 Corsair CMK48GX5M2B7000C40
- 2 x 16GB DDR5-8000 Corsair CMH32GX5M2X8000C36
- 2 x 24GB DDR5-8000 Corsair CMP48GX5M2X8000C38

With not focusing too much on desktop memory reviews at Phoronix given that there typically isn't a Linux angle from it, it's mostly a collection of DIMMs I've bought over time or a few have been received from vendors.

With this Intel Core Ultra 9 285K + ASUS ROG MAXIMUS Z890 HERO desktop I ran a variety of benchmarks on these different DIMMs in their XMP 1 profiles (or CUDIMM DDR5-6400 default given its lack of XMP profiles) for seeing how the Arrow Lake performance is impacted for a range of workloads.