Blinking Capslock and dead machine after intensive I/O on Precision 7710

Hi Folks,

   I have a pDell Precision 7710 with 16G RAM and the ATI graphics card.  Whenever I do a lot of writing to either a USB 2 storage device or a SDHC card, the machine locks up with blinking caps lock light after a few gigabytes have been transferred.

I'm running Linux with kernel 4.13.0-rc1 (but the problem has existed on all the kernels I've tested back to 3.10), and have the latest BIOS.

To reproduce the problem, do

  dd if=/dev/zero of=//mmcblk0 ***=1M

with a 4Gbyte or bigger SD card in the slot, otr do a similar tansfer to a USB stick.