I'm having a similar issue with the same HBA, but much slower speeds. 25-30MBps max, usually in the 15MBps range). I just migrated from a dual xeon server to a new i5 12400 with only two SATA slots on the motherboard. I intended all along to put all my drives onto the HBA but transfer speeds dropped dramatically. Reads, writes, on server, over the network are all the same even tho I upgraded to a 2.5Gbe network. I havent seen anything over 30MBps since I moved everything to the HBA. Currently reading a 3TB file from the array to a external USB3 drive, averaging 8.5MBps
Do I need to move two of the drives to the MB in order to get proper speeds?