I went into the BIOS and tried lowering the tREFI value from 6300 to 3150 (not sure what the units are). So far, it's gone 1000 iterations with no problems detected.
Edit: Actually, the units are probably multiples of the cycle time, just like CAS latency. So, for DDR3-1600, that would mean 6300x1.25ns=7.8μs, and 3150x1.25ns=3.9μs
Be careful not to run this test on machines that contain important
data. On machines that are susceptible to the rowhammer problem, this
test could cause bit flips that crash the machine, or worse, cause bit
flips in data that gets written back to disc.
**Warning #2:** If you find that a computer is susceptible to the
rowhammer problem, you may want to avoid using it as a multi-user
system. Bit flips caused by row hammering breach the CPU's memory
protection. On a machine that is susceptible to the rowhammer
problem, one process can corrupt pages used by other processes or by
the kernel.