W790 board for Sapphire Rapids: 64L and 112L CPUs both supported

SuperMicro X13SWA-TF for LGA 4677 socket Xeon W CPUs

One of December’s interesting news was the leak about Intel’s new Sapphire Rapids CPU platform for both high-end desktop (HEDT) and workstations. It’s three CPU platforms – but besides the 2S systems, we’re mainly interested in the two lineups for single-processor workstations: the pricier octo-channel Xeon W-3400 and the cheaper quad-channel Xeon W-2400 with fewer cores. But it looks like these two will be partially compatible.

According to the leaked information, Intel has three processor families ready for workstations. A somewhat special case will be the most powerful dual-processor (2S) workstation platform, because for this one, apparently chipsets and processors designed for servers (Sapphire Rapids-SP) will be used.

The other two platforms, which are single-processor only, are of more interest to us. According to leaked information, Intel will release both cheaper Xeon W-2400 processors (Sapphire Rapids-64L), which have a maximum of 24 cores, a controller for 64 PCI Express 5.0 lanes and quad-channel DDR5 memory. In addition, there will be a more expensive version, the Xeon W-3400 (Sapphire Rapids-112L) that has as much as 56 cores, 112 PCI Express 5.0 lanes and eight-channel DDR5 memory.

Read more: Intel’s new high-end desktop: W790 boards, quad-channel DDR5 and Sapphire Rapids-64L processors (platform descriptions, features, processor models and parameters)

Both of these processor versions are supposed to use W790 chipset boards, but we assumed that the “64L” version would use different (quad-channel only) boards than the 112L version, which will have different, eight-channel boards, similar to the separate TRX40 and WRX80 platform boards for Threadrippers.

The first W790 board in a photo

But now, a picture and specifications of one of the upcoming W790 platform boards has been leaked: the SuperMicro X13SWA-TF. And it appears that there will be some overlap. At least this board will support both versions of the processors at the same time – the cheaper one and the more expensive one. So W790 won’t be as fragmented as with Threadripper.

SuperMicro X13SWA-TF motherboard (source: Chiphell)

The SuperMicro X13SWA-TF is a large E-ATX motherboard with six PCI Express 5.0×16 slots, four M.2 slots with PCIe 5.0×4 connectivity, eight SATA ports, and two U.2 ports. As you can see in the photo through the clutter of Chinese text, this board has full 16 DIMM slots for DDR5 memory. A maximum of 4TB of RAM can be installed with 3DS RDIMM modules.

And according to the description, it supports both “Sapphire Rapids-64L” processors (i.e. Xeons W-2400 with up to 24 cores) and “Sapphire Rapids-112L” aka Xeons W-3400 with up to 56 cores. If you fit the second type of processor, then you have full functionality on the board – all six PCIe 5.0 ×16 slots and all 16 memory slots with eight-channel connectivity (eight slots for DDR5-4800, when fitting two slots per channel, i.e. 16 modules, only DDR5-4400 is officially supported).

With the cheaper Xeon W-2400 processor, not all of the connectivity can be used. This means that only three PCIe 5.0 ×16 slots will work. And the four-channel memory controller problem is solved the same way. With these processors in the socket, just half of the slots will work. You will only be able to use half the channels, so either four modules at full DDR5-4800 speed, or eight modules (but still in quad-channel mode) at DDR5-4400. But the important thing remains that despite these limitations, the cheaper processors will work in the same board. Though of course there is the problem that the board will be unnecessarily expensive for them.

Specifications for the SuperMicro X13SWA-TF (source: Chiphell)

56-core CPUs in cheaper four-channel boards?

The fact that Intel has designed both platforms to be compatible in this way gives hope that it could also work the other way around. There will probably be W790 boards with only four channels of memory (eight DIMM slots) and fewer PCIe 5.0 slots that will be sized exactly for the connectivity of the 64L version of the processor. But if it works the other way around, there’s a chance that you can also optionally stick the Xeon W-3400 processor (i.e. the 112L type) into these cheaper boards. While you won’t be getting the benefit of its PCIe 5.0 lanes and extra memory channels, it will give you the full number of cores – as much as 56, while the cheaper Xeon W-2400 processors will be 24-core at most. It would be like a hypothetical scenario where AMD allowed Threadrippers Pro to be fitted into TRX40 boards. Whether it can actually be done this way, we are not sure yet, but it would be quite welcome, because as seen with Threadrippers, fragmentation tends to be quite awkward in these lower-volume segments.

This particular board, the SuperMicro X13SWA-TF, is seemingly aimed at workstations and not the enthusiast desktop. The rather cramped power delivery with a relatively small heatsink gives it away, and it will probably need quite a bit of airflow directed on it when loaded with a 350W processor. And the board is also fitted with an Aspeed IPMI adapter for remote management. According to the description, the board probably does not allow overclocking, but the somewhat vague statement leaves open the possibility that an optional unlocked BIOS or a variant of the board with an unlocked BIOS allowing overclocking of the Xeon W-2400 or W3400 processors could still be released.

However, there should be specialized models from companies such as Asus, Gigabyte, MSI designed for more aggressive overclocking, that will be more reminiscent of enthusiast and gaming desktop boards.

Sources: VideoCardz, Chiphell, Harukaze5719

English translation and edit by Jozef Dudáš

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