Sent the board back, ebay seller was uncooperative but escalated case to ebay and received full refund.

If you're happy with 128GB max RDIMM's then there are a lot of options. Can find Lenovo D30, Dell T5610 cheap every now and then (eg $200AUD) (HP Z820 I have never found a cheap one), also ASUS Z9..D8 boards. If you want >128GB supermicro seems best option unless not concerned with noise - in that case could try to find a cheap HP ML350P gen8 or dell equivalent, but would need to add headsinks to handle >90W TDP cpus).