What markings do I need to look for in order to make sure that it I'll work with the board? Does it need to be a V3? Will a v4 work with a different board?Taken from this eBay link:
Intel Xeon E5-2630 v4 ES CPU 2.2GHz 10-Core 85W Max 3.1GHz QK3G Supports X99 MB | eBay
So even though it is an R0 stepping for your ASUS X99 motherboard it needs to be a QS or production processor to work properly. The QK3G is an ES2 (I would call it a pre-QS due to stepping ) with identical stepping as production.