Any more thoughts on cooling anyone?
You asked for it...
The only temperature issue you might possibly have is for the WD Red Pro 4TB hard drives, they are all 7200 RPM and generate some heat when not idle. These drive are certified to run at a maximum of 65C without voiding the warranty. Keep in mind that no one wants to run the hard drives at those temperatures. The possible option for you here is to use the WD Red Plus WD40EFZX drives which are 5400 RPM and draw less power which means less heat. The real difference otherwise between these two drives is the warranty length, 3 years vs. 5 years. Most hard drives will last 5 years regardless or they suffer from infant mortality (early death).
1. Due to your use case I highly recommend you use the WD40EFXZ drives vice the WD Red Pro's. This will make a difference on power draw and heat generated. So many people put four 7200 RPM drives together and are shocked with the heat created. They assume all will be fine, the drives were designed to work and they will just let them cook. It doesn't sound like you are one of those people since you are conserned about airflow and heat.
So let's say that you buy this system and everything works great except the hard drive temps are 55C, well you can drop the temps several C by doing a few things and I will list them. Keep in mind that I do not have the case you are purchasing and am using photos provided on a Google search.
2. Cover up any holes that allow air intake to force more air over the drives.
--- So this one is easy however while looking at the photos on the internet of this case, the only air intake I can see is the hole below the drive bays on the front of the case. This hole is to allow cool air in to flow across the motherboard. With this said, I'd first find out what the motherboard temps are and then only add some tape across half of the hole (find the elevation of the motherboard), if the board is above the hole then tape off the area below the board to force airflow across the motherboard upper components. But I didn't see anything else to cover up unless there are some holes on the bottom of the case. Also, a few small holes elsewhere are not a big deal, it's the larger openings that you should focus on.
3. Replace the Rear Exhaust Fan.
--- Now this is a very easy upgrade you can make. Buy a replacement High Air Flow and preferably quiet fan. You might pay up to $30 USD for a high quality fan but remember, it's cooling your system and on this case, it's the only fan. I suggest you do your research on fans looking for CFM, RPM, dBA. CFM high, RPM Low, dBA Low. I would buy something like the be quiet Silent Wings 4 fan, but seriously you should do some research, you would be surprised what you will find. If it's too cheap, don't buy it.
4. Exhaust Fan Case Modification.
--- The case manufacturers are cheap these days and the fan grill is a set of punched holes in the case metal, this is very inefficient. I myself will modify the case once and only after I know the case will work for me. In your case you have an integrated power supply so you need to make sure the case works well. I suspect that you would not make this modification until after you feel the case is not cooling well. But the steps I'd do are as follows. You will need to buy an appropriate wire fan grill for the fan, could be as low as $5 USD.
-- a. Remove everything from the case electronic. The motherboard, the power supply, the hard drive cages. This is going to depend on how much you prep the case for using a Dremel tool to cut metal and keep any metal debris out of the case. Clean-up is very important.
-- b. Use a marker to draw out exactly what you intend to cut out. You want to remove all the metal that covers the inside area of the fan. Do not go crazy and cut out everything at once unless you are certain you are not cutting it too large. You can't really add back metal unless you bolt back on a metal plate but that is a lot more work, but possible if needed.
-- c. Dry fit the fan and grill before cutting, make sure the marked up cutout looks right.
-- d. Wearing safety goggles (keep your eyes safe), Cut the metal. Clean up as you go. A vacuum works wonders.
-- e. Deburr the metal edges. This means make the edges as smooth as possible. Why? Because sharp edges cut human skin but more importantly they grab dust and then all that dust collects on those sharp edges. And lastly, it's pride is doing a good job.
-- f. Clean it all again, blow it our with compressed air if you have any.
-- g. Install the new fan and grill (the grill goes on the outside of the case, NOT the inside).
There are other things you could do to manipulate air flow within the case but just reach out if you do have problems keeping things cool and we can discuss it. If case modification like this are not your thing, well that is okay.
Seriously, buy the slower spinning drives. The will not impact your performance for the use case you described. If you were a data center then that is a different story.
