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BIOS Flashing Guide

Flashing the modded BIOS is essential for unlocking the BC-250's full potential. It enables dynamic VRAM allocation, overclocking, better fan control, and access to advanced chipset settings.

Critical First Step

ALWAYS clear CMOS after USB-based BIOS flashing. Settings will not stick properly otherwise, causing mysterious boot failures and RAM issues.

Why Flash the BIOS?

The stock BIOS has limited configuration options. The modded BIOS unlocks:

  • Dynamic VRAM allocation (512MB setting that auto-allocates between CPU/GPU)
  • Custom VRAM splits beyond the stock 8GB/8GB and 12GB/4GB options
  • Chipset menu access for advanced settings
  • Fan control improvements
  • Overclocking options (though GPU frequency is mainly controlled by governor)

Flashing Methods

There are two ways to flash the BIOS:

Pros: - No special hardware needed - Fast - Works on most boards

Cons: - Requires working board - Small risk of bricking (recoverable with hardware method) - MUST clear CMOS afterward

Method 2: Hardware Programmer

Pros: - Can recover from failed USB flash - Most reliable method - Can backup original BIOS

Cons: - Requires CH341A/CH347 programmer - More technical - Slower process

Recommendation

Start with USB method. Only get hardware programmer if USB flash fails or you want a backup option.

USB Flashing Method

What You Need

  • BC-250 board (with working stock BIOS)
  • USB stick (any size, FAT32 formatted)
  • Modded BIOS files
  • PC to prepare USB stick
  • DisplayPort cable or adapter (to access BIOS menu)

Step 1: Download BIOS Files

Get the latest modded BIOS from: https://gitlab.com/TuxThePenguin0/bc250-bios/

Download the .ROM file directly from GitLab.

Flashing Utility (Separate Download)

The BIOS flashing utility is available in the Discord server forum thread "BIOS update/flasher program". The GitLab link above only provides the BIOS ROM file itself.

What you'll need: - BC250_3.00_CHIPSETMENU.ROM - From GitLab link above - BIOS flashing utility - From Discord forum (includes PDF instructions)

BIOS Version

P3.00 is the recommended modded version. Your board may have P2.00, P4.00, or P5.00 stock - doesn't matter, flash to P3.00 modded.

Available BIOS Versions

P3.00 Chipset Menu (Recommended for most users): - Unlocks VRAM allocation, fan control, chipset settings - Most tested and stable by community - Download: TuxThePenguin0 GitLab

P5.00_clv (Newer, Advanced Users Only): - Contains many additional unlocked settings - Includes ReBAR (Resizable BAR) and other advanced options - Less tested, community reports "many settings you shouldn't touch" - Only use if you need specific advanced features - Shared in Discord #bc250-resources thread

Stock BIOS Version Differences

Stock BIOS versions (P2.00, P3.00, P4.00, P5.00) are functionally identical except:

  • P5.00 has network (PXE) boot enabled by default
  • P4.00 and earlier do not

"Robin" is the board's internal codename - all versions are for the same BC-250 hardware.

Community BIOS Archives

Complete stock BIOS packages with changelogs are available in the Discord server for reference: - Original ASRock engineering files - All stock versions (P1.00, P2.00, P3.00, P4.00, P5.00) - AfuLnx64 Linux flashing utility - Historical development context

Step 2: Prepare USB Stick

  1. Format USB stick as FAT32 (not exFAT or NTFS)
  2. Copy BIOS file to root directory
  3. Rename file to: robin5.00 (no file extension)

File Name Critical

The file MUST be named exactly robin5.00 (no .ROM extension). The bootloader looks for this specific name.

Step 3: Flash Using Utility

If using Windows:

  1. Download flashing utility from Discord forum
  2. Extract and run as administrator
  3. Select BIOS file
  4. Follow instructions in included PDF

If using Command Line Method:

  1. Copy renamed file to USB root
  2. Boot BC-250 with USB inserted
  3. Access boot menu (usually F11 or F12)
  4. Select USB device
  5. Flashing starts automatically

The process takes 2-5 minutes. Do not power off during flashing.

Step 4: Clear CMOS (CRITICAL)

Do Not Skip This Step

Failing to clear CMOS is the #1 cause of "BIOS settings won't stick" issues. The board will appear to work but RAM allocation won't apply properly.

Option A: Remove Battery (Recommended)

  1. Power off and unplug board
  2. Locate CMOS battery (CR2032 coin cell)
  3. Remove battery for 30 seconds
  4. Reinsert battery
  5. Power on

Option B: Use CMOS Jumper

  1. Power off and unplug board
  2. Locate CMOS clear jumper (check pinout diagram)
  3. Move jumper to clear position for 10 seconds
  4. Return jumper to normal position
  5. Power on

Step 5: Configure BIOS

On first boot after flashing:

  1. Press Del repeatedly during boot to enter BIOS
  2. Navigate to Chipset Configuration
  3. Find UMA Frame Buffer Size
  4. Set to 512MB (or desired fixed allocation)
  5. Optional: Set fan curves, disable unused ports
  6. Save and Exit (F10)

BIOS Navigation

Use arrow keys to navigate, Enter to select, F10 to save. Mouse doesn't work in BIOS.

Hardware Programmer Method

What You Need

  • CH341A or CH347 programmer ($10-30 on AliExpress/Amazon)
  • SOP8 test clip (usually included with programmer)
  • USB cable (usually included)
  • Another PC to run flashing software

BIOS Chip Location

The BIOS chip is located near the M.2 slot:

  • Chip Model: MX25L12835F or MX25L12873F (128Mb/16MB)
  • Package: SOP8
  • Position: Near PCIe slot, marked "BIOS" on some boards

Flashing Steps

  1. Download flashrom: 

    # Linux
sudo apt install flashrom  # Debian/Ubuntu
sudo dnf install flashrom  # Fedora

# macOS
brew install flashrom

  2. Connect programmer:

  3. Power off BC-250
  4. Attach SOP8 clip to BIOS chip (pin 1 indicator aligns)

  5. Connect programmer to PC via USB

  6. Backup original BIOS (recommended): 

    sudo flashrom -p ch341a_spi -r backup.bin
# Read twice and compare to verify
sudo flashrom -p ch341a_spi -r backup2.bin
diff backup.bin backup2.bin  # Should be identical

  7. Write new BIOS: 

    sudo flashrom -p ch341a_spi -w BC250_3.00_CHIPSETMENU.ROM

  8. Verify write: 

    sudo flashrom -p ch341a_spi -v BC250_3.00_CHIPSETMENU.ROM

  9. Disconnect and test:

  10. Remove clip
  11. Clear CMOS (same as USB method)
  12. Power on

Post-Flash Configuration

Essential BIOS Settings

After flashing, configure these critical settings:

Setting Location Recommended Value
UMA Frame Buffer Size Chipset → UMA 512MB
IOMMU Advanced → IOMMU Disabled
Fan Control H/W Monitor → Fan Control Customize (50-100%)
Boot Mode Boot → Boot Mode UEFI

VRAM Allocation Options

512MB (Dynamic) - Recommended: - Automatically allocates between CPU and GPU - Best for general use - May conflict with ZRAM in some games (use fixed instead)

Fixed Allocations: - 10GB RAM / 6GB VRAM - Good for AAA games - 8GB RAM / 8GB VRAM - Balanced - 12GB RAM / 4GB VRAM - Light gaming, more system RAM

Detailed VRAM guide →

Known Post-Flash Issues

DisplayPort Audio Compatibility

Some users report DisplayPort audio issues after flashing modded BIOS:

  • Audio may be pitched down/slow ("slow motion" effect)
  • Affects some older TVs/monitors, works fine on modern displays
  • Passive DP-to-HDMI adapters work better than active ones
  • Flashing back to stock may NOT resolve the issue

Workarounds: - Use passive DP-to-HDMI adapter (not active) - Try USB audio adapter - Test with different display if possible - Modern 4K HDR displays typically don't have this issue

Troubleshooting

USB Flash Failed / No Response

Symptoms: - USB boot doesn't start - Flashing hangs

Solutions: 1. Verify USB is FAT32 formatted 2. Check file is named exactly robin5.00 3. Try different USB stick 4. Ensure file is in root directory (not in folder) 5. Try different USB port

Board Won't Boot After Flash

Symptoms: - No display - Power on but nothing happens - Fan spins but no boot

Solutions: 1. Clear CMOS again (most common fix) 2. Check power connections (8-pin firmly seated) 3. Try hardware programmer recovery 4. Reseat RAM (some boards have removable RAM)

BIOS Settings Don't Stick

Symptoms: - Set 512MB but system still shows 8GB/8GB split - Settings reset after reboot - Changes don't apply

Solution: Clear CMOS properly. This is almost always the cause.

  1. Remove CMOS battery for 60 seconds (not just 10)
  2. With battery removed, press power button 5 times (discharges capacitors)
  3. Reinsert battery
  4. Boot and reconfigure

Display Shows But BIOS Menu Won't Appear

Symptoms: - Board boots to black screen - No BIOS logo - Can't access BIOS setup

Solutions: 1. Try different display cable/adapter 2. Spam Del key earlier (right when powering on) 3. Try F2 or F12 instead 4. Check monitor is set to correct input

Accidentally Flashed Wrong File

Recovery: 1. If board still boots: Flash correct file via USB 2. If board doesn't boot: Use hardware programmer with backup BIOS

BIOS Recovery

If USB Flash Bricked the Board

  1. Order CH341A programmer
  2. While waiting, verify it's actually bricked:
  3. Check all power connections
  4. Try clearing CMOS again
  5. Test with different display adapter
  6. When programmer arrives, follow hardware method above
  7. Flash known-good BIOS file

If No Backup BIOS Available

Community members have uploaded stock BIOS dumps:

  • Stock P2.00: Available in Discord #bc250-resources
  • Stock P3.00: Available on GitLab
  • Stock P5.00: Available in community archives

Join Discord server (link in GitHub) for assistance.

Verification

After successful flash and configuration:

# Check VRAM allocation in Linux
cat /proc/meminfo | grep -i mem
# Should show ~10-12GB depending on your split

# Check GPU detected
lspci | grep VGA
# Should show AMD Radeon Graphics

# Verify BIOS version
sudo dmidecode -t bios
# Should show P5.00 or your modded version

FAQ

Q: Can I flash without clearing CMOS? A: Technically yes, but you'll have weird issues. Always clear CMOS.

Q: Will this void my warranty? A: These boards are sold "as-is" with no warranty anyway.

Q: Can I revert to stock BIOS? A: Yes, flash your backup or download stock BIOS and flash it.

Q: Do I need to reflash when updating Linux? A: No, BIOS is independent of OS.

Q: What if power fails during USB flash? A: Board may be bricked. Recover using hardware programmer.

Q: Can I flash from Linux? A: The USB method requires booting the BC-250 itself. Hardware programmer works from any OS running flashrom.

Next Steps: - VRAM Configuration Guide - Recovery Guide