Half the memory bus, half the bandwidth
HKEPC has published what appears to be the first hands-on performance test of DDR5 HUDIMM , a cut-down memory design that keeps only one 32-bit sub-channel instead of the two 32-bit sub-channels used by standard DDR5 UDIMM modules. The site says the test was carried out with ASUS support and used a BIOS that recognizes HUDIMM operation.
This is not a retail HUDIMM kit review. HKEPC says it simulated the format by masking one 32-bit sub-channel on a normal DDR5 DIMM with tape , then booting the system with HUDIMM-capable firmware. In the demo, the BIOS still identified the module as a 16GB G.Skill stick, but the information page showed 8GB effective capacity, while CPU-Z reportedly detected the memory as running in “1x 32-bit” mode.
Source: HKEPC
HKEPC’s AIDA64 test showed the modified 8GB 1×32-bit configuration at 32,447 MB/s read, 25,195 MB/s write, and 26,894 MB/s copy. A regular 16GB dual-channel module reached 58,913 MB read, 48,800 MB/s write, and 52,648 MB/s copy. HKEPC summarizes the drop at 44.9% in read, 48.4% in write, and 48.9% in copy, while latency stayed close, around 86 to 88 ns.
- [8GB – 1 x 32-bit Single Channel] 1 DIMM (Disabled)
- 32,447 MB/s Read, 25,195 MB/s Write, 26,894 MB/s Copy, 87.7ns
- [16GB – 2 x 32-bit Single Channel] 1 DIMM Unblocked
- 58,913 MB/s Read, 48,800 MB/s Write, 52,648 MB/s Copy, 85.7ns
- [16GB – 1 x 32-bit Dual Channel] 2 DIMMs are blocked.
- 58,928 MB/s Read, 48,461 MB/s Write, 51,473 MB/s Copy, 86.5ns
- [32GB – 2 x 32-bit Dual Channel] 2 DIMMs, unblocked
- 106.02 GB/s Read, 93,235 MB/s Write, 97,522 MB/s Copy, 86.4ns
Source: HKEPC
Source: HKEPC
One of the more interesting points is that two HUDIMM modules in dual-channel reportedly perform at about the same level as one normal DDR5 DIMM. HKEPC’s data showed the “16GB, 1 x 32-bit dual channel” setup at roughly 58.9 GB/s read, which is almost identical to the “16GB, 2 x 32-bit single channel” result from one unmodified.
Source: HKEPC
