Open your case and see if it looks like this photo: http/data.stuartconnections.com/object/image?p=10873&i=5
If so, any low-profile version of that card should fit fine. But you may run into a problem with the small power supply in the desktop. The R7-240 is a 30W card maxed out. That's an additional 2.5A on the +12V rail. I suspect you won't have any problem, but if you keep getting shutdowns or reboots when gaming, it will probably be due to the weak PSU.
Open your case and see if it looks like this photo: http/data.stuartconnections.com/object/image?p=10873&i=5
If so, any low-profile version of that card should fit fine. But you may run into a problem with the small power supply in the desktop. The R7-240 is a 30W card maxed out. That's an additional 2.5A on the +12V rail. I suspect you won't have any problem, but if you keep getting shutdowns or reboots when gaming, it will probably be due to the weak PSU.