Inside the Cooler Master ATCS 840 we had mounted a Tyan Tempest i5400XT motherboard, dual Intel Xeon 5300 Clovertown quad-core processors with Dynatron heatsinks, 2GB of Kingston DDR2 FB-DIMM RAM, a Seagate SATA HDD, SATA DVD-RW drive, Sapphire Radeon HD 4850 graphics card, and a Hiper Type-M 780W power supply. Everything had mounted very easily and we were still left with plenty of room. We had not run into any issues with the removable motherboard tray or any other areas and it was simple a very nice and efficient installation.
When running the hardware within this chassis we had not experienced any thermal issues or other problems. The chassis was also surprisingly quiet aside from the dual Dynatron heatsinks that can become quite noisy at times. No single fan included with this case has a noise level above 19 dBA.
Cooler Master is highly regarded among computer enthusiasts and gamers for building quality products and with the ATCS 840 this still holds true. The ATCS 840 is an extremely large case that can accommodate dual ATX power supplies, an EATX motherboard, six disk drives, and six external 5.25" drives. You could also run multiple GPUs in this system too quite well on top of that.
With this case being so large and heavy though, this is not an ideal candidate to be transporting to LAN parties or gaming events and you may even have problems fitting this case underneath your desk. Aside from the space requirements, the case is very nice and is well designed. The only weak area of this case we feel is the plastic HDD holders, which are a bit flimsy, but we hadn't experienced any real problems with them.
If you are looking for a large case to fit a lot of hardware in and are looking for other features like air filters, removable motherboard tray, and easy cable management, the Cooler Master ATCS 840 is a great fit and will only set you back about $250 USD.