In order to access the memory of your machine properly DMA devices require you to disable virtualization on your machine. Make the following changes in your BIOS:
Disable Virtualization (AMD)
Disable IQMMU (AMD CBS > NBIO Common Options > NB Configuration > IOMMU)
Disable Virtualization (INTEL)
Disable VT-d
Disable NX-Bit (if available, CPU Settings Secure Virtual Machine)
Set PCI Slot of Card to From Auto to Gen1 (Advanced > PCI Settings)
Once you modified your BIOS Settings it is important to turn off your PC after saving/rebooting. Otherwise the changes will not be activated.