DDR5 4 DIMMs 6400 Mt/s possible on 285k?

[Codrut]

Motherboard: Asus ProArt Z890 Creator WiFi

CPU: Core 9 Ultra 285k

Memory. 4 DIMMs, 2 x Crucial DDR5 Pro 6400 64 GB (specifically 2 x CP2K32G64C40U5B)

I could boot with 4 DIMMs only at 6000 MT/s XMP enabled

When choosing 6400 it does not boot, it seems to hang in the memory training phase.

Is it possible to run 4 DIMMs at 6400 MT/s with a 285k CPU? Or is it too hard for the CPU to handle 4 DIMMs?

[pressed_for_time]

If you want to run 6400 MT/s memory in all four DIMM slots then you need to check for compatible memory on the Memory support page for your motherboard which can be found here . The graphic below shows the result of specifying 6400 MT/s and four DIMM slots

I appreciate that it's a disappointment that your 6400 MT/s memory chips only run at 6000 speed in four slots. But for unsupported memory this seems to me to be a reasonable result.

[Codrut]

Yes, 6000 is reasonable and it's rock solid, I even purchased Karhu RAM test which supposedly detects issues faster than any other memory testing app and it's very stable at 6000. I would buy the new CU-DIMMs but they are not too available yet and very expensive.

[PC1997]

"According to the current Intel processor specifications (XMP disabled), DDR5 4800 speed may drop to as low as 4200 when four DIMM slots are populated.

Ensure that all memory modules are from the same validated memory kit. Do not mix DIMMs from different memory kits—even if they are the same brand and model (e.g., two DIMMs each from two different memory kits).

The stability and compatibility of memory kits operating beyond the POR standard, such as XMP (Intel), D.O.C.P, EXPO (AMD), AEMP series, are not guaranteed, as they can be affected by the CPU‘s memory controller and the devices installed.

The default DIMM frequency depends on its Serial Presence Detect (SPD), which is the standardized way of accessing information from a memory module. Under the default state, some memory modules for overclocking may operate at a lower frequency than the vendor-rated value. To reach the kit’s rated speed, please select XMP(Intel)/D.O.C.P/EXPO(AMD) or manually configure the settings.

Overclocking memory involves boosting memory frequency or tightening timings. Increasing memory frequency can boost read and write speeds while tightening timings can improve copy and latency performance. In gaming, low latency is often more important than high frequency.

When installing a memory kit, please adhere to the DIMM slot priority cited in the product manual’s Memory installation section."

So the answer is probably No. Try CU-DIMMs from the same manufacturer AND the same ram kit. DO NOT mix ram kits, EVEN if they are the same – they are not.

While this can work, as you've already seen, you will run into trouble.

[Codrut]

Perhaps someone knows if this new CUDIMMs can run at 6400 MT/s? I could not find them for buying anywhere yet, but I guess they will be available in a few months. I would like to have 256 GB of memory running at full 6400 MT/s. Perhaps the new chip on CUDIMMs helps?

[PC1997]

CU-DIMM's will simply give you a better chance to run higher frequencies, but you are overclocking your RAM with 4 dimms at 6000 MT/s. While your CPU officially supports 6400 MT/s memory, this is only official for 2, not 4 dimms.

[Codrut]

I just wanted to report that with the latest BIOS update and after activating the 200S Boost my 4 x DDR5 DIMMs now runs at 6400 MT with no problem. I haven't tried anything else, like overclocking. Now my DIMMs work at their specifications