DMA Troubleshooting Guide
Common errors, their causes, and how to fix them
Most DMA problems come down to a handful of common causes. This guide covers every error you're likely to encounter and how to fix it, starting with the most common one.
VMM INIT FAILED
This is the most common DMA error. It appears when the DMA connection is hung or stale. A cold boot of the gaming PC fixes this in 99% of cases.
The error happens because a warm reboot (clicking Restart in Windows) does not fully reinitialize PCIe devices. The DMA card's link state gets stuck.
- Shut down the gaming PC completely from Windows (Start → Shut Down, not Restart)
- Wait 5 to 10 seconds
- Power back on
Reading the diagnostic numbers
The error output contains version numbers that tell you what's wrong:
[0,v0.0,0000]
No USB/DATA connection at all. Check the FTDI driver, cable, and port. Make sure you're plugged into the DATA port, not JTAG.
[3,v4.x,0000] or [4,v4.x,0400]
USB link is working but DMA reading fails. Check BIOS settings (VT-d/IOMMU disabled, Secure Boot off, Kernel DMA Protection off). Reseat the DMA card, try a different PCIe slot. On AMD systems, generate a memory map.
FTDI driver issues
"Unable to load 'FTD3XX.dll'"
The DLL is missing from your PCILeech/MemProcFS working directory. Download the 64-bit FTD3XX.dll and place it alongside your executables.
"Unable to connect to USB/FT601 device [0,v0.0,0000]"
No USB connection exists at all. Verify the cable is in the DATA port (not JTAG), the FTDI D3XX driver is installed, and you're using a USB 3.0 port.
"FTDI SuperSpeed-FIFO Bridge" shows yellow exclamation
The D3XX driver isn't installed yet. Run the FTDI installer as administrator and restart.
Driver was replaced after Windows Update
Windows Update silently replaces the FTDI driver with a generic one. Open Device Manager, right-click the device, Update Driver, Browse my computer, and point to the extracted FTDI driver folder's x64\Win10 subfolder.
Memory map issues (AMD systems)
AMD systems and Thunderbolt connections have memory holes that crash the DMA connection when read. Symptoms include:
- "Unable to locate valid DTB"
- "Unable to auto-identify operating system"
- DMA working briefly then stopping
How to generate a memory map
- Download RAMMap from Microsoft Sysinternals
- Run RAMMap64.exe on the gaming PC as administrator (close all games and anti-cheats first)
- Save as .RMP file via File → Save
- Transfer to the reader PC
- Convert using an MMAP converter tool
- Place the resulting
mmap.txtalongside your DMA software - Launch with the
-memmap mmap.txtflag
-memmap auto flag is deprecated and may produce errors.Slow speeds
If your speed test shows under 3000 Mem/sec, troubleshoot in this order:
- Replace the USB cable with a certified USB 3.0 data cable. This is the fix 80% of the time.
- Try a different USB port on the reader PC (motherboard only, no hubs)
- Set power plan to High Performance on the reader PC
- Reseat the DMA card in its PCIe slot
- Check the card bracket isn't blocking the USB cable from seating fully
- Try a different PCIe slot on the target PC
- Try PCIe Gen2 in BIOS if you're on Gen1 and the card is otherwise stable
If you see "Tiny PCIe TLP Algorithm" in the output, the firmware's config space may be incompatible with the motherboard. Try a different PCIe slot or check your firmware.
Flashing errors
"JTAG scan chain interrogation failed: all zeroes/all ones"
No JTAG connection exists. Verify the cable is in the JTAG port and the target PC is providing power to the card.
Device not detected in Device Manager
Try a different USB cable and a different USB 3.0 port. For CH347 cards, make sure the CH341PAR driver is installed.
CH347FPGATool crashes on start
The firmware file path contains spaces. Move the tool and firmware to a simple path like C:\CH347FPGATool\.
Wrong Zadig interface selected
Always change Interface 0 only in Zadig. Selecting the wrong interface can cause issues with the DMA card.
Windows updates breaking DMA
Windows updates can break DMA by:
- Re-enabling Kernel DMA Protection
- Replacing FTDI drivers with generic ones
- Updating BIOS on OEM systems
- Resetting VBS/Core Isolation settings
After any Windows update:
- Check
msinfo32for "Kernel DMA Protection" status - Verify BIOS settings haven't been reset
- Check Device Manager for the correct FTDI driver
- Re-check Windows Security → Core Isolation settings
Hardware failure vs firmware corruption
Signs of firmware corruption (fixable)
- USB connects and shows a firmware version but PCIe ID reads 0000
- Card worked previously but stopped after a failed flash
- JTAG programmer can still connect to the card
Fix: Reflash the firmware via JTAG. If the JTAG programmer can connect, the FPGA hardware is fine.
Signs of hardware failure (not fixable)
- Zero LED activity in any system
- JTAG programmer unable to connect at all
- Card causes crashes when inserted
- Visible physical damage
Test in a different system to isolate the variable. Same failure across systems points to the card. Working in another system points to BIOS, slot, or settings on the original system.
Quick reference error table
| Error | Meaning | Fix |
|---|---|---|
VMM INIT FAILED |
Stale DMA connection | Cold boot gaming PC |
Unable to load 'FTD3XX.dll' |
DLL missing | Place DLL alongside executables |
Unable to connect [0,v0.0,0000] |
No USB connection | Check cable, driver, port, power |
[x,v4.x,0000] |
USB works, PCIe not enumerated | Reseat card, check slot, cold boot |
TINY PCIe TLP Algorithm |
Low speed mode | Fix USB cable/port, check firmware |
Unable to locate valid DTB |
Memory map needed | Generate MMAP from RAMMap |
info.db not found |
Offline symbols missing | Download info.db from MemProcFS releases |
Failed to retrieve Physical Memory Map |
Unstable USB | Reseat cable, try different port |