So, I wouldn't give up that easily. What I'd try next is bumping up the DRAM voltage since you're running four DIMMs.
The advertised memory kit speed, timings and voltage are generally, especially in a case like this where you are not running ONE kit that all came together, but two kits comprised of two DIMMs each, intended to only be good if using only two DIMMs.
Since you are running four, and especially since this is a multiple kit situation, I'd try enabling XMP and then increasing the DRAM voltage in the advanced memory section incrementally, by .005v increments (Or whatever the smallest increment it will allow you to increase it by is for that board model). Increase by .005v, save setting, exit BIOS, see if it will POST. If not, back into BIOS, increase by another .005v, save settings, rinse and repeat. If it doesn't work by the time you get to 1.4v then it probably isn't ever going to and at that point I'd be willing to make the assumption that the problem is simply down to incompatibility between the two kits regardless that they are the same packaged model number.
There can be anything from identical composition to highly different configurations between memory kits that are the same model if they did not come off the assembly line during the same production run, and sometimes even then, which is why they get tested together for compatibility before they are packaged together and sent out the door.
You can read more about that here if you are interested.