What's CUDIMM Memory?

Note the marked IC in the middle of the memory module. With Arrow Lake, Intel is introducing support for CUDIMM DDR5 memory, which stands for "Clocked Unbuffered Dual Inline Memory Module." These DIMMs represent an advancement over standard DDR5 memory by incorporating a CKD (Clock Driver) chip directly on the memory modules. Instead of having to drive each memory chip individually, over a relatively long distance, the CPU can now send a signal to just the Clock Driver, which then drives the memory chips directly over a short distance, which helps with signal integrity, especially at high clock frequencies.


G.SKILL sent us their upcoming F5-8800C4255H24GX2-TZ5CK, a 2x 24 GB DDR5-8800 CUDIMM memory kit—very impressive. We will be using this in an upcoming Arrow Lake Memory Scaling article. For now, see below for some quick results.

Performance Scaling

To get a feel for performance improvements with faster memory, we ran some benchmarks using G.SKILL's CUDIMM DDR5-8800 memory kit with the Ultra 9 285K. Please note that this is a different test setup than our regular main test suite, so the results are not directly comparable, despite the same test names.
We're using a Noctua NH-D15 for temperature measurements. Application temperatures are measured using Blender, a highly demanding rendering load, which will load all cores completely, but that's still realistic and is not a synthetic stress test such as Prime95. For gaming, we picked Cyberpunk 2077, its modern engine is multi-thread aware and will try to spread as many tasks as possible over many CPU cores, when available. Even when a game uses multiple threads it doesn't load each CPU core as heavily as rendering, for example, so there's some scope for power savings here.

Note that unless indicated otherwise, all processors are tested at stock conditions with their power limit active, which is why some Intel temperatures are surprisingly low. As designed by Intel, these CPUs can exceed their TDP for a few seconds (PL2), but in the long term, the power limit (PL1) is respected, which brings temperatures down considerably. Both tests report the steady-state temperature after an extended runtime of at least 10 minutes. Temperatures are based on delta T, normalized to 25°C, that's why the temperature of some CPUs is higher than their throttle point, because the room temperature was below 25°C.

For recent Intel CPUs we've increased the temperature limit in BIOS from 100/105°C to 115°C, to get a better feel for temperatures without thermal throttling getting in the way.

AMD Zen 4 and Zen 5 CPUs have their thermal target set to 95°C, which means the CPU will boost as much as it can, until it reaches that point, to maximize performance. Unlike on Intel, on AMD's AM5 platform it's not possible to increase the 95°C limit.

Temperature testing on this page uses air-cooling, for consistency and to show comparable results. All performance testing on the other pages is done using an Arctic Cooling Liquid Freezer III liquid cooling solution that keeps the temperatures well below all limits, to ensure there is no thermal throttling.