It's not really bigger than Standard ATX, or it would have to be listed as a form factor other than ATX. With the false floor on the Element G it may be a tight squeeze, but I see no reason for it to not fit. It just may not be all that knuckle-friendly.
If you're at all worried about space, I know it's overused, but perhaps the HAF 932 would be more your speed. http://www.newegg.com/Product/Produc...82E16811119160 It has great airflow, more space to work in than the Element, and is built like a tank. It is a big case, though, so it may not be what you're looking for. My only concern is that the false floor of the Element may be nice sometimes, but it may become an annoyance when you are first building. I know because my case has a false floor, and it makes CF/SLI probably not an option unless single-slot cards start coming out again, and attaching USB and front panel leads to the motherboard was a bit of a pain.

If you're at all worried about space, I know it's overused, but perhaps the HAF 932 would be more your speed. http://www.newegg.com/Product/Produc...82E16811119160 It has great airflow, more space to work in than the Element, and is built like a tank. It is a big case, though, so it may not be what you're looking for. My only concern is that the false floor of the Element may be nice sometimes, but it may become an annoyance when you are first building. I know because my case has a false floor, and it makes CF/SLI probably not an option unless single-slot cards start coming out again, and attaching USB and front panel leads to the motherboard was a bit of a pain.