chore: moved the newly added article to the correct directory and removed the draft parameter
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+++
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title = "BC-Zero - Board Testing"
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summary = "From an old mining board to a console and AI server"
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date = "2026-11-08"
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tags = ["BC-250", "PS5", "Unlock", "BIOS", "CPU", "GPU"]
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categories = ["Projects"]
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series = ["BC-Zero"]
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series_order = 1
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+++
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On February 5th, [Soffio](https://t.me/Soffioo), a friend and fellow
|
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[LUGMan](https://lugman.org/) member, made me discover a peculiar board: the
|
||||
**BC-250**.
|
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|
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The BC-250 is a board that comes from an [ASRock cryptocurrency mining
|
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rig](https://www.tomshardware.com/news/twelve-ps5-apus-power-asrocks-new-cryptomining-rig),
|
||||
which housed twelve of them.
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|
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Inside each of these boards there's a *binned* chip derived from the AMD APU of
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the PlayStation 5, with 6 of the 8 CPU cores and 24 of the 36 GPU CUs enabled,
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along with 16GB of GDDR6 RAM **unified** between CPU and GPU, an M.2 slot (PCIe
|
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2.0x2 or SATA III), and just a few ports: two USB 2.0, two USB 3.0, one Gigabit
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Ethernet, and one DisplayPort. Power is supplied through an 8-pin PCIe
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connector.
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At first I wasn't really convinced, especially seeing a third of the CUs cut off
|
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and knowing that it's a board with a custom, partially locked chip (on top of
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the locked cores, some features like video encoding/decoding are missing),
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coming from cryptocurrency mining and with no support or community behind it.
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But the price was definitely interesting, and apparently this board has a very
|
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active community that works hard to squeeze 100% of its potential out of it on
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Linux.
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Things changed when, on the morning of May 30th, I got this message:
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||||
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||||
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And good old Soffio also pointed out that the AliExpress sales were about to
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start. Intrigued by the whole thing, I asked him if he could lend me his board
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for a few days, just to try it out and see what could be done.
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And *oh boy*, did this board convince me.
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## Step 0: Preparation
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||||
|
||||
One downside of the BC-250 is that it's not exactly *plug-and-play*. At the very
|
||||
least, you need to:
|
||||
|
||||
1. Find a power supply that can ***really*** deliver at least 300W on the +12V
|
||||
rail, with cables that can handle all those amperes;
|
||||
2. Have a monitor with DisplayPort (or buy an adapter);
|
||||
3. Find a way to cool the damn thing;
|
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4. Flash the BIOS.
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|
||||
My test setup was:
|
||||
|
||||
1. The first "*el cheapo*" power supply I could find lying around (which "will
|
||||
surely be fine, it says 500W");
|
||||
2. A passive DP ➜ HDMI adapter;
|
||||
3. A portable air conditioner for cooling (it was summer and it was starting to
|
||||
get hot);
|
||||
4. A CH341 SPI programmer (which I already had).
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|
||||
|
||||
|
||||
Not exactly the best setup for testing the board, but you work with what you
|
||||
have.
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|
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## Step 1: Flashing the BIOS
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|
||||
The [first step in the community
|
||||
documentation](https://elektricm.github.io/amd-bc250-docs/getting-started/quick-start/#step-1-bios-flash-critical)
|
||||
is flashing the BIOS. Without a custom BIOS you don't get essential features
|
||||
like dynamic VRAM allocation (remember, the 16GB of RAM are shared) and proper
|
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fan control.
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|
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At first I installed the one recommended by the guide, the one by
|
||||
[TuxThePenguin0](https://gitlab.com/TuxThePenguin0/bc250-bios), but later on I
|
||||
discovered another BIOS, the one by [Forbidden
|
||||
Darkness](https://github.com/Forbidden-Darkness/AMD-BC-250-UEFI-v2.2-Firmware-Menu-Script),
|
||||
which, on top of unlocking the dynamic allocation menu, offers a selection of
|
||||
custom splash images and, most importantly, **unlocks all 8 CPU cores**.
|
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|
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"*Wait, weren't they locked down?*" Apparently not enough.
|
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|
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The APU has all cores on the silicon, they're just disabled via firmware. A
|
||||
similar principle also applies to the GPU CUs, but we'll get to that later.
|
||||
|
||||
---
|
||||
|
||||
The installation is even simpler and doesn't require a BIOS flasher: just copy
|
||||
the files from the `.7z` archive in the releases to a USB stick formatted in
|
||||
FAT32 and boot from it. The installer asks which splash image we want (the
|
||||
[`07`](https://github.com/user-attachments/assets/ca23ce6c-08ab-4293-9a70-0e55f66dc93c)
|
||||
is the best one, *imho*) and proceeds with the flashing.
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||||
|
||||
|
||||
|
||||
{{< alert icon="triangle-exclamation" cardColor="#e6d237" iconColor="#1d3557"
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||||
textColor="#1d3557" >}}
|
||||
Flashing the BIOS is a dangerous operation. Make sure the board doesn't turn
|
||||
off.
|
||||
{{< /alert >}}
|
||||
|
||||
Once the flashing is done, you need to reset all the BIOS settings. To do that,
|
||||
just unplug the power and bridge pin 2 and 3 of the `CLRCMOS1` header for a few
|
||||
seconds. Once that's done, we can put the header back on pins 1 and 2 and plug
|
||||
the power back in. By entering the BIOS with the `Del` key at boot we'll see a
|
||||
lot more options.
|
||||
|
||||
|
||||
|
||||
|
||||
First, let's make the VRAM allocation automatic. To do that, we need to go to
|
||||
`Chipset` > `GFX Configuration` > `GFX Configuration` and set `Integrated
|
||||
Graphics Controller` to `Forces`, then `UMA Mode` to `UMA_SPECIFIED`, and
|
||||
finally `UMA Frame buffer size` to `512M`.
|
||||
|
||||
|
||||
|
||||
Then in `NB Configuration` disable the IOMMU (it doesn't seem to work on this
|
||||
board).
|
||||
|
||||
Finally, we enable all the cores by going to `Advanced` > `MeiMeiDXEv3 Menu` and
|
||||
enabling everything.
|
||||
|
||||
|
||||
|
||||
{{< alert icon="triangle-exclamation" cardColor="#e6d237" iconColor="#1d3557"
|
||||
textColor="#1d3557" >}}
|
||||
There's no guarantee that all the cores will work. Damaged cores could cause
|
||||
sudden crashes.
|
||||
|
||||
To avoid that, we'll run a stress test on all the cores and check that no
|
||||
`Machine Check Exception` shows up in the kernel logs before enabling this
|
||||
setting in production.
|
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{{< /alert >}}
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||||
|
||||
Once the BIOS is properly configured, we're ready to install an operating system
|
||||
and test this board for real.
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|
||||
## Step 2: Installing a OS for testing
|
||||
|
||||
To do some CPU stress testing and run some tests on the GPU, I'll install Arch
|
||||
Linux.
|
||||
|
||||
It won't be the final distro I'll install, but the choice isn't random:
|
||||
development for this board is bleeding-edge, and for now almost all the scripts
|
||||
assume you're running Arch or Fedora, so you have the latest package versions.
|
||||
|
||||
|
||||
|
||||
|
||||
### Testing the 8 cores
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||||
|
||||
First of all, let's test whether all 8 cores work as they should. To do that,
|
||||
install the `stress-ng` package and run a stress test:
|
||||
|
||||
```sh
|
||||
stress-ng --cpu 16 --cpu-method all --verify --timeout 2h --metrics
|
||||
```
|
||||
|
||||
Then we check that there were no errors with:
|
||||
|
||||
```sh
|
||||
sudo dmesg | grep -iE "mce|machine check|hardware error"
|
||||
```
|
||||
|
||||
If the kernel doesn't report any errors, we've just gone from 6 to 8 cores for
|
||||
free. If there is an error you can change which cores to enable from the BIOS.
|
||||
|
||||
### Stress-testing the GPU
|
||||
|
||||
Next, let's stress test the GPU to get a performance baseline before installing
|
||||
the governor or enabling all the CUs. To do that, I installed Furmark and ran
|
||||
the 1080p test.
|
||||
|
||||
|
||||
|
||||
I'd say 70 FPS isn't *that* bad for the board *out-of-the-box*, but we can
|
||||
definitely do better, much better.
|
||||
|
||||
---
|
||||
|
||||
A small note I feel I should add: if during the stress test the screen goes
|
||||
black and the board doesn't respond in any way, check your power supply. The
|
||||
little foreshadowing I did in step 0 about the power supply is because during my
|
||||
tests I ran Ollama and completely fried the PSU since (apparently) it couldn't
|
||||
really handle the whole load on the +12V rail. I then bought the PSU recommended
|
||||
by the community on AliExpress, along with the board, the [Metalfish 500W
|
||||
FlexATX](https://elektricm.github.io/amd-bc250-docs/hardware/power#option-2-flexatx-psu-500w),
|
||||
and I haven't had any problems since.
|
||||
|
||||
|
||||
|
||||
### Installing the GPU Governor
|
||||
|
||||
By default the GPU always runs at 1500MHz: a governor lets you raise the clock
|
||||
when the GPU is under load and lower it when it isn't, to save power.
|
||||
|
||||
We'll install `cyan-skillfish-governor-smu`, a community project that talks
|
||||
directly to the board's System Management Unit. It's also already packaged in
|
||||
the AUR, so to install it you just need to run:
|
||||
|
||||
```sh
|
||||
paru -S cyan-skillfish-governor-smu
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||||
systemctl enable --now cyan-skillfish-governor-smu
|
||||
```
|
||||
|
||||
We can check that it works with:
|
||||
|
||||
```
|
||||
$ cat /sys/class/drm/card1/device/pp_dpm_sclk # If it doesn't work, try card0
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||||
0: 1000Mhz *
|
||||
1: 1500Mhz
|
||||
2: 2000Mhz
|
||||
```
|
||||
|
||||
The first and last lines are, respectively, the minimum and maximum GPU
|
||||
frequency, while the middle line can change. The asterisk marks the frequency
|
||||
currently in use. An example under load:
|
||||
|
||||
```
|
||||
$ cat /sys/class/drm/card1/device/pp_dpm_sclk
|
||||
0: 1000Mhz
|
||||
1: 1850Mhz *
|
||||
2: 2000Mhz
|
||||
```
|
||||
|
||||
We should see the GPU automatically use a higher frequency under load and a
|
||||
lower one when idle.
|
||||
|
||||
---
|
||||
|
||||
**Small note**: unlocking the 8 cores affects how the SMU values are read. It's
|
||||
a known issue and we'll fix it later on, when we'll deal with the operating
|
||||
system. Without any fix, the frequency values are wrong, for example:
|
||||
|
||||
```
|
||||
$ cat /sys/class/drm/card1/device/pp_dpm_sclk
|
||||
0: 1000Mhz *
|
||||
1: 4575Mhz
|
||||
2: 2000Mhz
|
||||
|
||||
# Not a bad overclock for a chip that tops out at 2230MHz
|
||||
```
|
||||
|
||||
With that said, let's run a stress test now, with the governor installed.
|
||||
|
||||
|
||||
|
||||
Now that we can scale up to 1850MHz, our GPU manages to reach 83 FPS at 1080p,
|
||||
not bad!
|
||||
|
||||
1850MHz is by no means the most this chip can handle, but for now we'll settle
|
||||
for it. For the curious, the frequency and voltage curves are fully customizable
|
||||
and live in `/etc/cyan-skillfish-governor-smu/config.toml`. With a bit of trial
|
||||
and error you can push the hardware to its limits while minimizing power draw,
|
||||
but we'll do that when we set up the final operating system.
|
||||
|
||||
### Unlocking the 40 CUs
|
||||
|
||||
As we said at the beginning, this board only exposes 24 CUs to the kernel, even
|
||||
though the PS5 has 36 and there are actually 40 on the silicon. We can verify
|
||||
this with:
|
||||
|
||||
```
|
||||
$ sudo dmesg | grep active_cu_number
|
||||
[ 6.882856] amdgpu 0000:01:00.0: SE 2, SH per SE 2, CU per SH 10, active_cu_number 24
|
||||
```
|
||||
|
||||
To test and then unlock all the CUs, we'll use [duggasco's
|
||||
repository](https://github.com/duggasco/bc250-40cu-unlock). The mechanism is
|
||||
similar to the core unlock: here too you just need to change a few values,
|
||||
because the CUs aren't locked at the hardware level, they're just disabled by
|
||||
the firmware.
|
||||
|
||||
Two registers in the GPU decide how many CUs are active. What this script does
|
||||
is patch the `amdgpu` driver and write the right values into those registers
|
||||
while the driver starts up, waking up the disabled CUs.
|
||||
|
||||
```
|
||||
$ git clone https://github.com/duggasco/bc250-40cu-unlock.git
|
||||
$ cd bc250-40cu-unlock/
|
||||
$ sudo pacman -S linux-headers vulkan-headers
|
||||
$ sudo scripts/bc250-enable-40cu-arch.sh build
|
||||
|
||||
# Wait for the `amdgpu` module to be recompiled
|
||||
|
||||
$ sudo scripts/bc250-enable-40cu-arch.sh enable
|
||||
```
|
||||
|
||||
Once the BC-250 has rebooted, we can check that the patch worked using the same
|
||||
command as before:
|
||||
|
||||
```
|
||||
$ sudo dmesg | grep active_cu_number
|
||||
[ 8.004012] amdgpu 0000:01:00.0: SE 2, SH per SE 2, CU per SH 10, active_cu_number 24
|
||||
|
||||
```
|
||||
|
||||
Apparently the script doesn't load the custom module automatically. That's not a
|
||||
problem: let's regenerate the initramfs and reboot manually:
|
||||
|
||||
```
|
||||
$ sudo mkinitcpio -P
|
||||
$ reboot
|
||||
|
||||
# Once it has rebooted
|
||||
$ sudo dmesg | grep active_cu_number
|
||||
[ 8.058999] amdgpu 0000:01:00.0: SE 2, SH per SE 2, CU per SH 10, active_cu_number 40
|
||||
```
|
||||
|
||||
Much better!
|
||||
|
||||
---
|
||||
|
||||
Once the custom module is installed, we can move on to testing the CUs:
|
||||
|
||||
```
|
||||
$ sudo scripts/bc250-cu-health-test.sh start
|
||||
```
|
||||
|
||||
During the test the PC will automatically reboot twenty times. Once the PC stops
|
||||
rebooting on its own, we can see the test results with:
|
||||
|
||||
```
|
||||
$ scripts/cu_map.sh
|
||||
|
||||
BC-250 CU Map + Health
|
||||
SE0 SH0: ■■■■■■■■■■
|
||||
SE0 SH1: ■■■■■■■■■■
|
||||
SE1 SH0: ■■■■■■■■■■
|
||||
SE1 SH1: ■■■■■■■■■■
|
||||
40/40 CUs active, 0 harvested
|
||||
|
||||
BC-250 CU Map + Health
|
||||
SE0 SH0: ■■■■■■✓✓✓✓
|
||||
SE0 SH1: ■■■■■■✓✓✓✓
|
||||
SE1 SH0: ■■■■■■✓✓✓✓
|
||||
SE1 SH1: ■■■■■■✓✓✓✓
|
||||
40/40 CUs usable (0 defective, masked)
|
||||
```
|
||||
|
||||
Apparently I won the silicon lottery and have 8 cores and 40 working CUs.
|
||||
Hurray! 🎉
|
||||
|
||||
If there had been any defective CUs I could have masked them using the
|
||||
`bc250-cu-mask.sh` script.
|
||||
|
||||
---
|
||||
|
||||
Running the last stress test with Furmark:
|
||||
|
||||
|
||||
|
||||
We went from the bare board, without any additional software, running at an
|
||||
average of 70 FPS, to having a governor and all the CUs unlocked, with peaks of
|
||||
138 FPS, twice as much!
|
||||
|
||||
Of course, this approach to unlocking the 40 CUs has a pretty obvious problem,
|
||||
especially on rolling distributions like Arch: you have to recompile the module
|
||||
every time you update the kernel. This is another problem we'll solve later on,
|
||||
when we stop using a test OS, but if after an update the GPU isn't as fast as
|
||||
before, it might be worth taking a look.
|
||||
|
||||
### Sensors and Other Essential Configurations
|
||||
|
||||
Once the essentials like CPU and GPU are sorted out, there are still a few small
|
||||
things to take care of, such as sensor management, fans, swap, VRAM split,
|
||||
etc...
|
||||
|
||||
I could go on about it for hours, but I'll point you to the [community
|
||||
documentation](https://elektricm.github.io/amd-bc250-docs/), which is very
|
||||
thorough.
|
||||
|
||||
What I'd like to do now is point out one thing: using the `sensors` command, we
|
||||
get very little data OOTB:
|
||||
|
||||
```
|
||||
$ sensors
|
||||
amdgpu-pci-0100
|
||||
Adapter: PCI adapter
|
||||
vddgfx: 799.00 mV
|
||||
vddnb: 799.00 mV
|
||||
edge: +39.0°C
|
||||
PPT: 41.41 W (avg = 40.85 W)
|
||||
sclk: 1000 MHz
|
||||
|
||||
k10temp-pci-00c3
|
||||
Adapter: PCI adapter
|
||||
Tctl: +41.6°C
|
||||
```
|
||||
|
||||
To get more data we need the `nct6683` module (read-only) or `nct6687` (you can
|
||||
create custom curves with it, but it's *out of tree*). Since `nct6683` is
|
||||
already available, we can enable it with:
|
||||
|
||||
```
|
||||
$ echo 'options nct6683 force=true' | sudo tee /etc/modprobe.d/sensors.conf
|
||||
$ echo 'nct6683' | sudo tee /etc/modules-load.d/99-sensors.conf
|
||||
$ sudo mkinitcpio -P
|
||||
$ reboot
|
||||
```
|
||||
|
||||
After rebooting we'll see a lot more data:
|
||||
|
||||
```
|
||||
$ sensors
|
||||
k10temp-pci-00c3
|
||||
Adapter: PCI adapter
|
||||
Tctl: +46.9°C
|
||||
|
||||
amdgpu-pci-0100
|
||||
Adapter: PCI adapter
|
||||
vddgfx: 799.00 mV
|
||||
vddnb: 799.00 mV
|
||||
edge: +41.0°C
|
||||
PPT: 42.61 W (avg = 40.75 W)
|
||||
sclk: 1000 MHz
|
||||
|
||||
nct6686-isa-0a20
|
||||
Adapter: ISA adapter
|
||||
VIN0: 800.00 mV (min = +0.00 V, max = +0.00 V)
|
||||
VIN1: 1.01 V (min = +0.00 V, max = +0.00 V)
|
||||
VIN2: 992.00 mV (min = +0.00 V, max = +0.00 V)
|
||||
VIN6: 1.39 V (min = +0.00 V, max = +0.00 V)
|
||||
VIN7: 800.00 mV (min = +0.00 V, max = +0.00 V)
|
||||
VIN16: 896.00 mV (min = +0.00 V, max = +0.00 V)
|
||||
fan1: 0 RPM (min = 0 RPM)
|
||||
fan2: 1709 RPM (min = 0 RPM)
|
||||
fan3: 0 RPM (min = 0 RPM)
|
||||
fan4: 0 RPM (min = 0 RPM)
|
||||
fan5: 0 RPM (min = 0 RPM)
|
||||
AMD TSI Addr 98h: +47.0°C (low = +0.0°C)
|
||||
(high = +0.0°C, hyst = +0.0°C)
|
||||
(crit = +0.0°C) sensor = AMD AMDSI
|
||||
Thermistor 14: +37.0°C (low = +0.0°C)
|
||||
(high = +0.0°C, hyst = +0.0°C)
|
||||
(crit = +0.0°C) sensor = thermistor
|
||||
Thermistor 15: +37.0°C (low = +0.0°C)
|
||||
(high = +0.0°C, hyst = +0.0°C)
|
||||
(crit = +0.0°C) sensor = thermistor
|
||||
pwm1: 64%
|
||||
pwm2: 64%
|
||||
pwm3: 64%
|
||||
pwm4: 64%
|
||||
pwm5: 64%
|
||||
intrusion0: OK
|
||||
beep_enable: disabled
|
||||
```
|
||||
|
||||
## Step 3: Hardware Mods
|
||||
|
||||
I want to remind you that for all these tests I was using Soffio's BC-250, just
|
||||
to see whether it was something I'd be interested in. And since I found myself
|
||||
pretty hooked I decided to get everything I needed from AliExpress.
|
||||
|
||||
Luckily with the sales and also using TopCashback I managed to bring home
|
||||
everything I needed for less than €200. I then bought a couple of Arctic P12
|
||||
Pros from Amazon.
|
||||
|
||||
Everything arrived on June 24th, so it was time to get to work on:
|
||||
|
||||
* Replacing the thermal paste and pads;
|
||||
* Installing heatsinks on the back panel, to cool the GDDR6;
|
||||
* Removing the metal bracket and the I/O shield (they're only needed if the
|
||||
board is mounted in the rig);
|
||||
* Re-running the test suite mentioned above to see if I had won the silicon
|
||||
lottery a second time (luckily I did);
|
||||
* Modding the heatsink.
|
||||
|
||||
The heatsink mod let me solve one of the problems I was having with the board:
|
||||
how do I get rid of 200W of heat? So far I had the portable AC, but I couldn't
|
||||
keep using a heat pump to cool a single board.
|
||||
|
||||
When they're in the mining rig, the BC-250 all have their heatsinks laid out
|
||||
lengthwise, so a single array of fans is enough to cool all 12 boards at once.
|
||||
If you want to use one of these boards on its own, you need to get a bit more
|
||||
creative to get rid of the heat.
|
||||
|
||||
The most common solution in the community is the [heatsink
|
||||
mod](https://reddit.com/r/BC250Gaming/comments/1rjc3io/), which consists of
|
||||
literally cutting open the heatsink in the section above the APU to make room
|
||||
for a fan.
|
||||
|
||||
It's a somewhat long and tedious job, but it's not impossible to do. It's also a
|
||||
pretty repetitive task, so once you get the hang of it, it goes by farely
|
||||
quickly. In the end all it took was a pair of scissors, some good music, and an
|
||||
hour of my time.
|
||||
|
||||
|
||||
|
||||
|
||||
It's a bit *rough around the edges* (*literally*), but it works. And the hole is
|
||||
big exactly as a 120mm fan, so one of the two fans can blow directly onto the
|
||||
APU.
|
||||
|
||||
---
|
||||
|
||||
Since this article has gotten pretty long, I've decided to split it into
|
||||
multiple parts. In the next one, we'll design a custom case for my needs.
|
||||
Reference in New Issue
Block a user