Lah Kara

October 2021

Pitch

A RISC-V mini-ITX immersion-cooled Linux workstation.

Compute

  • SiFive Unmatched: 4+1 RISC-V cores at 1.5GHz, 16GB RAM, in Mini-ITX form factor.
  • Intel AX-200 Wifi 6 / Bluetooth 5 adapter.
  • 1TB NVMe M.2 SSD. I’ve got a double-sided high performance one from a previous build, and if it’s not compatible I’ll get something like a Samsung 970 Evo.
  • RX 570 4GB graphics. The goal here is not high perfomance (not a gaming rig), but something that can handle a few screens and only need a PCIe Gen 3 interface.

Cooling

  • Wide-gap slant-fin heat sinks to replace the OEM fin array (PCIe chip) and fan (CPU).
  • Extension cabling for USB and Ethernet.
  • I’m undecided whether I’ll strip the fans off the graphics card and attempt to immerse it, or if I’ll get a riser/extension to bring it outside.

Immersion fluid (oil)

Requirements:

  • Boiling and smoke points above 120C
  • Liquid at room temperature
  • Long shelf life (doesn’t go rancid quickly)

Nice to haves:

  • Fairly clear or transparent (for aesthetics)
  • Edible / non-toxic
  • Doesn’t stink!

The “long shelf life” requirement basically reduces the possibility set to:

  • Mineral oil (petroleum, colorless, odorless, non-edible, but not touch-toxic, quite cheap)
  • Ben oil (golden, edible, fairly soft smell, 200C smoke point, very expensive)

So as much as I’d love having a veggie oil computer I’ll probably go with mineral.

Case

I’m thinking of making a custom acrylic/copper/solid wood box that would be roughly the size of a classic mini-ITX case. A copper side would be the thermal interface, and it could be sealed to make it portable and safe from spills (not permanently glued, with a rubber seal or something), so it can sit on the topside of the desk looking all cool!

  • Base: solid wood (Macrocarpa)

Naming

I name all my devices in a Star Wars theme. Workstations (desktop, laptops) after minor characters, phones and tablets after vehicles, and IoT / utility devices (vacuum, printer, routers, various SBC things, etc) after droids. My wifi network is named after a star system. I’m a nerd, sue me.

Lah Kara is from the new Visions series.

OS

Either FreeBSD or Ubuntu (or both?).

FreeBSD

Tier 2 platform support, many packages fail to build.

Ubuntu

Unknown support but they have images and repos.

Media