if you updated the BIOS you should just run memtest on its own boot image to see if the memory timings are ok.
each BIOS has different ways of setting up the memory timing and some just never tell you how they are set up and just tell you that you have to use memory from a memory compatibility list that they provide. Also, if you have two types of ram, the BIOS will set all the memory timings to one setting. You might have to set the timings to the slowest RAM module timing settings. You might try removing all the ram except the new ram, boot into bios and reset it back to defaults
save the settings, power down and install the rest of the ram and power back up. This might force all the ram to run with the slower timings...