In December 2019 I heard from Goran who had added a hard disk to his H710C.
First step was to check the hard drive worked with the H710C. One metal lug on the case had to be bent out of the way to achieve this.
The next step was to work out where to mount it.
His first thought was to put it in the add-on foot, but noticed that it actually fitted very nicely if he dispensed with the PCIe riser (which he wasn't using) and mounted it above the heatsink.
Another benefit here was the mounting brackets for the riser were almost a perfect fit for the hard drive. (Within 1mm).
Reversing the mounting brackets positioned the drive about 10mm clear of the heatsink.
With the H710C standing on its foot the drive actually just hangs vertically from mountings. The fact that the other edge of the drive is not supported is not really an issue.
He also added a fan to assist with cooling. This was a 40mm square fan that was superglued to the top of the chassis. He subsequently decided that this was a little noisy and a better choice might have been a 50mm x 50mm fan.
The fan was powered from the unused SATA_PWR1 socket.
Here is a view of the internals of the finished item. He used separate SATA data and power cables and plugged the data cable into the stand-alone data socket.
I don't know why, but these sorts of connection cables all seem to come in fairly long lead lengths. When ever I do something like this I am always left with the problem of how to tidy away the extra length of cable. You can see here that Goran has made a neat job of it.
The finished item. The top is not completely fitted - in fact it is propped open with a clothes peg (not ideal - but just happened to be to hand). He's also added a couple of strips of tape inside the case over the metal mesh at the top of the sides to ensure the air flow to the fan passes up through the body of the H710C and isn't just sucked in from the sides at the top.
The current/min/max/average temperatures for the CPU and hard drive shown whilst running a stress test.
As the Igel 710C had a PCIe expansion slot I was reminded of John's solution on a HP t610. He used a carrier made by Akasa for one or two hard drives that was designed to fit in a PCI or PCIe slot. I don't know if there is sufficient space in the H710C to accommodate one of these.
There are also alternatives to the Akasa that are listed on eBay. I found a suitable eBay search term to be:
(pci,pci-e,pcie) (drive,disk) (bracket,mount,mounting)...but Goran's solution is cheaper!