From 796471cc6e2d3d2cad0e0b9b04349a6595365d0b Mon Sep 17 00:00:00 2001 From: Martin Date: Wed, 18 Mar 2026 23:48:22 +0100 Subject: [PATCH] feat: add technical facts from Discord resource channels - display.md: DisplayLink unreliable (latency, no game mode), DP MST max 2 screens - cooling.md: 3 heatsink variants (QR code = 9-row), thermal pads 1.5mm front/2.0mm back - distributions.md: Ubuntu 26.04 daily server ISO works out of box - radv.md: LLM headless mode tip (~14.2GB available VRAM, headless saves ~800MB) - stability.md: P5.00 BIOS more susceptible to bricking from memory timing; tREF most rewarding timing, GDDR6 ICs are bottom-binned Micron --- docs/drivers/radv.md | 11 ++++++++++- docs/hardware/cooling.md | 3 ++- docs/hardware/display.md | 6 ++++-- docs/linux/distributions.md | 4 ++-- docs/troubleshooting/stability.md | 3 +++ 5 files changed, 21 insertions(+), 6 deletions(-) diff --git a/docs/drivers/radv.md b/docs/drivers/radv.md index 9c8c970..ce58bbe 100644 --- a/docs/drivers/radv.md +++ b/docs/drivers/radv.md @@ -614,9 +614,18 @@ export GGML_VK_FORCE_MAX_ALLOCATION_SIZE=2000000000 # 2GB chunks **Performance:** - 4-bit quantized 8B model: ~60 tokens/sec -- 12GB VRAM split recommended for larger models +- ~14.2 GB available VRAM with desktop running, 256-512MB BIOS VRAM setting sufficient (dynamic allocation handles the rest) - Vulkan backend more stable than ROCm for BC-250 +**Tip: Headless mode for maximum VRAM:** +```bash +# Disable GUI to free ~800MB RAM for inference +sudo systemctl set-default multi-user.target && sudo reboot + +# Restore GUI later +sudo systemctl set-default graphical.target && sudo reboot +``` + **Known Issues:** - Vulkan sees ~10GB of 12GB VRAM (see VRAM visibility issue above) - Large models (70B+) may OOM even with quantization diff --git a/docs/hardware/cooling.md b/docs/hardware/cooling.md index 27b1402..a92e126 100644 --- a/docs/hardware/cooling.md +++ b/docs/hardware/cooling.md @@ -10,6 +10,7 @@ The BC-250 requires active cooling for gaming and desktop use. This guide covers - **Fin Orientation:** Vertical, front-to-back - **Design Purpose:** Rack-mounted passive or low-airflow cooling - **Desktop Use:** Inadequate without active airflow +- **Variants:** Three heatsink variants exist (8-row and 9-row fins). Quick ID: a QR code next to the PCIe 8-pin connector indicates the 9-row variant. The variant with fewer, thicker-gauge aluminum fins may cool slightly better stock. !!!warning "Active Cooling Required" The stock heatsink is designed for rack airflow, not desktop use. Add a fan for gaming workloads. @@ -245,7 +246,7 @@ GDDR6 memory chips on the underside can run hot under sustained load. **Solution:** 1. Remove board from case 2. Remove old thermal pads (if present) -3. Apply new thermal pads (1.5mm-2mm thick) +3. Apply new thermal pads (**1.5mm on front of board, 2.0mm on back**) 4. Attach aluminum plate or heatsink to underside 5. Optional: Add fan for active cooling diff --git a/docs/hardware/display.md b/docs/hardware/display.md index e1e5f42..fc77451 100644 --- a/docs/hardware/display.md +++ b/docs/hardware/display.md @@ -237,11 +237,13 @@ glxinfo | grep "OpenGL renderer" **Option 1: USB DisplayLink Adapter** - Add USB to HDMI/DisplayPort adapter -- Works for desktop use -- Not suitable for gaming (high latency) +- Works for desktop use (plug in after boot for best results) +- **Not suitable for gaming** — high latency due to CPU-based compression, BC-250's CPU is the bottleneck +- Does not work in Steam Deck game mode **Option 2: DisplayPort MST Hub** - Split single DP into multiple displays +- **Maximum 2 screens** via MST on BC-250 - Shares bandwidth between displays - Works for productivity - Limited resolution per display diff --git a/docs/linux/distributions.md b/docs/linux/distributions.md index 406dd48..a7c39bd 100644 --- a/docs/linux/distributions.md +++ b/docs/linux/distributions.md @@ -266,8 +266,8 @@ pacman -S base-devel cmake git mesa vulkan-radeon ### Ubuntu **Status:** Works with updated Mesa -- **Mesa:** 25.1.5 available via PPAs -- **Kernel:** 6.12+ recommended +- **Mesa:** 25.1.5 available via PPAs. Ubuntu 26.04 daily server ISO includes Mesa 25+ and kernel 6.17/6.18 with out-of-box BC-250 support. +- **Kernel:** 6.18.x LTS recommended - **Desktop:** GNOME by default **Pros:** diff --git a/docs/troubleshooting/stability.md b/docs/troubleshooting/stability.md index 0bdbf33..c8d8634 100644 --- a/docs/troubleshooting/stability.md +++ b/docs/troubleshooting/stability.md @@ -432,6 +432,9 @@ zram-size = 4096 # 4GB instead of 8GB **Quote**: > "Its not actually 450, its like 1750, but you can modify it. I wouldn't recommend it though, ppl over in the russian BC250 chat reported that unstable ram settings would frequently result in BIOS corruption, requiring the BIOS to be reflashed" +!!!danger "P5.00 BIOS More Susceptible to Bricking" + Community reports (from the Mem Timing Utility channel) indicate **P5.00 BIOS** is more susceptible to permanent bricking from aggressive memory timings, requiring a full reflash. **P3.00 BIOS** typically triggers a watchdog reset instead. The most rewarding timing to tune is tREF; other UDIMM timings yield minimal gains. The BC-250's GDDR6 ICs are bottom-binned Micron parts with limited overclocking headroom. + **If you must overclock RAM**: 1. Have hardware flasher ready (CH341A or Raspberry Pi Pico) 2. Back up working BIOS first