Friday, September 5th 2025
GIGABYTE AI TOP CXL R5X4 Card Adds 512GB Memory to Xeon and Threadripper Systems
GIGABYTE has launched its AI TOP CXL R5X4 expansion card that can boost system memory by up to 512 GB using CXL technology. The AI TOP CXL R5X4 plugs into a PCIe 5.0 x16 slot and works with CXL 2.0/1.1 standards. It has four DDR5 RDIMM slots, each supporting memory modules up to 128 GB with ECC. This setup is different from built-in CXL options like Samsung CMM-D modules as it uses regular DDR5 memory so you have more choices for how much memory to add. The card is 120 mm x 254 mm and has a 16-layer HDI PCB. At full load, it uses about 70 W of power and needs an 8-pin EXT12V plug to work. An LED on the card shows if it's powered up while a single AIO fan cools the Microchip PM8712 controller.
Compatibility is still limited to certain GIGABYTE motherboards. Right now, the supported platforms include the TRX50 AI TOP for AMD Threadripper processors and W790 AI TOP for Intel Xeon systems. Also, CXL functionality isn't supported by all PCIe slots on these motherboards. The TRX50 AI TOP's PCIEX16_4 slot, for example, lacks CXL compatibility. GIGABYTE recommends contacting the company before purchase to verify system compatibility. There's no official pricing yet, although industry estimates suggest a $2,000-$3,000 retail price range based on comparable CXL products.
Sources:
IT Home, Club386, GIGABYTE AI TOP CXL R5X4
Compatibility is still limited to certain GIGABYTE motherboards. Right now, the supported platforms include the TRX50 AI TOP for AMD Threadripper processors and W790 AI TOP for Intel Xeon systems. Also, CXL functionality isn't supported by all PCIe slots on these motherboards. The TRX50 AI TOP's PCIEX16_4 slot, for example, lacks CXL compatibility. GIGABYTE recommends contacting the company before purchase to verify system compatibility. There's no official pricing yet, although industry estimates suggest a $2,000-$3,000 retail price range based on comparable CXL products.
29 Comments on GIGABYTE AI TOP CXL R5X4 Card Adds 512GB Memory to Xeon and Threadripper Systems
:laugh:
[I know they're fundamentally different devices. Still, funny that this isn't Gb's first 'slot-in DRAM card']
In seriousness,
seeing these kinds of CXL cards come to market makes me hopeful that all those surplus Optane DCPMMs might someday be useful (again)
I feel ya though.
Hoping this 'kind' of AIC will become more common, and *maybe* if we're really really lucky...
we'll see CXL on next/coming-gen desktops.
4 CCD (24-32 cores) Threadripper (7000 series) supports about 167-179 GB/s (4 memory channels)
4 CCD (24-32 cores) Threadripper Pro (7000 series) supports about 236 GB/s- 246 GB/s (8 memory channels)
8 CCD (64 cores) Threadripper (7000 series) supports about 240 GB/s (4 memory channels)
8 CCD (64 cores) Threadripper Pro (7000 series) supports about 453 GB/s (8 memory channels)
12 CCD (96 cores) Threadripper Pro (7000 series) supports about 720 GB/s (8 memory channels)
PCIe gen5 x16 supports up to 64 GB/sec speeds.
Why to add lot of expensive memory behind a very slow bus?
That Gigabyte ramdrive card was nice but same as this, mostly overpriced for what it did, so it never evolved or became more common.
EDIT: Here is the PDF specification for the controller: ww1.microchip.com/downloads/aemDocuments/documents/DCS/ProductDocuments/Brochures/SMC-2100-Smart-Memory-Controllers-00005431.pdf
It supports both DDR4 and DDR5 and there's also PCI-E x8 / 1 DDR channel version.
Dedicated LLM workspaces
Dedicated/Assigned DMA pool
NtM sometimes, they might just need even more RAM and the platform just cannot be expanded further.
A 5200MHz DDR5 stick with its 64-bit bus provides 41.6GB/s of theoretical bandwidth, so that's your theoretical bandwidth per channel.
A 4-channel system of the above would provide 166.4GB/s, 8-channel would be 332.8GB/s
Even at 6000MHz with 8-channels it'd be at 384GB/s.
Anyhow, 64GB/s is more than a single channel of DDR5 memory, so one could think of those CXL memories as adding one extra channel with tons of extra capacity.
4 of those? 4 extra channels, with up to 2TB of extra capacity, which is not bad at all.
But these enterprise chips from Microchip are always very expensive, same with PCI-E switches (if anyone is wondering, why motherboards don't have them anymore to offer more slots... this is why, they start at $250 for 24 total in+out lanes... for gen3!).
Still would be fun to play with this thing... so might pick one up on sale on Aliexpress in about 10 years... :rolleyes:
threadripper/comments/1azmkvg/comparing_threadripper_7000_memory_bandwidth_for
I use a lot the DRAM for file storage. I will not bother with windows as Windows Vista does not exsits anymore, 7, 8, 8.1 and 10 soon. I do not waste my time with an os which may work or not with DRAM. My operating system was installed on hardware which shipped with windows Vista. 5x or more reinstalls needed by now with windows.
For a pure windows desktop box with word or a pure windows gaming box this product may not matter anyway.
See the whole reddit thread. The OP provided more calculations and explanations after the initial post. Those huge numbers over 700 GB/s are the bandwidth between the IOD and the CCDs.
Table 1: Experimental platform. “Local” refers to the performance measured by CPUs on the same socket while “+NUMA” indicates memory access from a remote socket.
The authors of the previously referenced paper presented at ASPLOS 2025 (link to PDF) where the DRAM configuration was different and the number of channels were included in the table. I have adapted the table below from the newer paper.
I don't recall there being issues w/ non-ECC, but it was kind of a niche device for rapid-swapping whole system images. I imagine it was primarily used by HWbot'ers and Benchmarkers.