I have installed a new EPICS IOC (dac_overflow_rate_ioc) which for each model calculates the per second increase in the accumulated DAC overflow counter. If the rate is non-zero, the upper block of the DAC Overflow square in the CDS Overview turns yellow. The lower block shows dark green if the accumulated counter is non-zero (i.e. overflows in the past which have not been cleared).

The new IOC runs on the service host cluster, it is monitored by a "DAC OVERFLOW" system block at the bottom of the CDS Overview.

Please note that the accumulated DAC overflows wrap-around at 0x1000000 (just over 16 million) to prevent the number on the MEDM becoming too large to be read.