My Experience with the ASRock BC-250 (Unlocking 40 CUs)

The ASRock BC-250 is a fascinating piece of hardware. Originally released during the ~~crypto gold rush~~ of 2021/2022 as a dedicated mining card, it was essentially rendered obsolete when Ethereum transitioned away from proof-of-work. This left a surplus of units—some never even unboxed—scattered across defunct mining farms.

"Thanks to the diligent efforts of community members capable of writing technical documentation, the BC-250 now enjoys full native support on Linux."

The "Binning" Loophole

The card's appeal lies in AMD's somewhat lax binning process. They often failed to fuse off faulty cores, meaning users can potentially unlock more performance than officially advertised.

Acquisition & Costs

I picked up two units using a combination of back-to-school sales and PayPal's interest-free credit options.

Unit A: Purchased for £126.
Unit B: Purchased for £103.
- Note: There is a pending refund of £29.38 expected in a few months.

To find the effective cost of Unit B, we can use the following calculation: $\text{Effective Cost} = 103 - 29.38 = 73.62$ (The author notes this as effectively £74.06).

Hardware Comparison

Feature	Unit A (£126)	Unit B (£103)
Compute Units (CUs)	40 Unlocked	40 Unlocked
CPU Cores	8 (All functional)	7 (One faulty)
Status	Fully Operational	"Reeee" moment (but okay for servers)

Technical Setup & Benchmarking

For the software side, I utilized llama.cpp with the Vulkan backend to benchmark the gpt-oss-20b model.

Setup Checklist:

Install Linux native drivers
Unlock 40 CUs
Configure llama.cpp
Optimize thermals

To power the build, I used a CORSAIR CX550. While not a top-tier PSU, it handles the BC-250 easily. I snagged it for £30 (plus a separate UK plug) via Amazon Resale. It was listed as "Used Very Good," likely because people avoided it following poor results from Labs.

Thermal Management

The BC-250 is notoriously difficult to cool. I implemented some non-engineer "optimizations":

Airflow: Used tape to direct air more efficiently.
Thermal Mass: Added several mini stick-on heat sinks to the top to help spread heat.

Market Outlook

The "Golden Era" of the BC-250 is likely ending. With a Linus Tech Tips video on the horizon and a Switch and Click video already live, demand will likely spike. Interestingly, the card featured in the Switch and Click video only unlocked 28 CUs (an extra 4), which is the lowest I've seen.

Sourcing Tip: While some buy from eBay, I recommend AliExpress. I sourced mine from the seller SZ HONGXUNJIE ELECTRONIC.

# Example command for running the benchmark
./main -m gpt-oss-20b.gguf --n-gpu-layers 40 -ngl 40