The Corsair Obsidian 750D and the Airflow edition are much more expensive at NewEgg which makes it hard to compare prices. At least the H115i water cooler is close to MSRP.
The larger Obsidian 750D is more spacious inside which makes it easier to work on and it also makes it slightly easier to manage cables.
The H115i water cooler is overkill but it does provide some panache when posting a photo online. The H115i is a large 280mm water cooler that can handle 200W overclocked processors with ease. The R5 2400G is 65W with the Vega graphics active and 46W when a video card is installed.
At present the 750D is backordered due to its popularity. Checking around with Google found many vendors and there are still a few available.
Corsair has the 750D priced at $159.99 Canadian and there is a link to notify when available. NewEgg wants $239.99 + 9.99 shipping with a $20 rebate card. Ordinarily NewEgg adjusts prices when currencies move relative to one another. Occasionally discrepancies are apparent.
The 750D is good for the person who has vast numbers disks installed. The 750D disk cages hold 3 disks each and more are available from Corsair. With a SATA card a large number of disks can be in use to handle disks galore.
The existing SPEC-01 is functional but its a tight squeeze to have the machine loaded up. There are 4 hard disks installed which is the maximum. More can be added to the LAN easily as network storage.
The disks in the SPEC-01 are warm so adding another fan in front of the chassis is an option. The MSI X470 motherboard has several fan headers making it possible to monitor the front fans as well as the CPU and rear fans. Red LED fans are available.
The old Cooler Master HAF 932 is still viable and while it needs some minor.repairs the old chassis can be put to use quickly.