Asrock, Intel, and Teamgroup: HUDIMMs for cheaper DDR5

Taiwanese manufacturer Asrock has announced the new “HUDIMM” DRAM concept for its desktop mainboards. These are memory modules for the conventional DDR5 slot with 288 contacts. However, the internal structure of the “half unbuffered DIMMs“ – hence the name – differs. Therefore, only Teamgroup will initially produce the HUDIMMs. The concept has Intel's blessing and is designed to work with chipsets from the 600, 700, and 800 series, meaning all current Intel processors.

The goal is cheaper memory modules with DDR5. Prices for conventional DIMMs have sometimes quadrupled in the last seven months because huge amounts of DRAM are being bought up for AI data centers at almost any price. Asrock and Co. want to counter this by using half as many DRAM chips on a HUDIMM for the same capacity.

Only a 32-bit channel in a HUDIMM

To achieve this, one of the two sub-channels is omitted. Unlike DDR4 with a uniform 64-bit channel for each DRAM channel – usually with up to two slots – DDR5 provides two channels of 32 bits each. This fits better with the data structures of x86 processors and allows, among other things, short pauses against overheating during read and write operations. The disadvantage: To utilize the two 32-bit sub-channels, the same number of chips must be installed for each sub-channel on the DIMM. The DIMM boards also become more complex.

Teamgroup can now combine DRAM chips with larger capacities, which are already preferred in production due to the AI hype, into one channel. In theory, this results in HUDIMMs with a comparable amount of memory to conventional DIMMs, but with fewer chips, traces, and thus costs. However, the companies involved have not yet provided specific price information.

Strange performance comparison

With only one instead of two sub-channels, the question of performance arises. Asrock presented a somewhat crude comparison with a mixed configuration. Since HUDIMMs are logically and mechanically compatible with previous DDR5 DIMMs, the following construct is possible: a HUDIMM with 8 GByte (one sub-channel) and a DIMM with 16 GByte (two sub-channels). According to Asrock's measurements, this combination, with three sub-channels, should be minimally faster than a single DIMM with two sub-channels. Thus, a dual-channel configuration from the mainboard's perspective is compared with a single-channel configuration, both with 24 GByte. Furthermore, AIDA64 is a synthetic benchmark, not one with real applications.

However, if memory performance is not crucial for the specific application, such as for office PCs, but capacity is more important, a single HUDIMM could indeed offer cost advantages. Asrock has not yet revealed how fast it will be. HUDIMMs are also expected to appear in SO-DIMM format, including for the Deskmini series of particularly compact PCs. According to the company, the technology is patented, so it remains to be seen whether other manufacturers will support HUDIMMs. Asrock boards will require a firmware update to use the new memory modules, which is expected to be available here in the future.

(nie)