you might run acu in 1024x768 with r7 240, but not with E7400.
acu has a very large number of AI/NPC in game which needs atleast 4 cpu core. that's why it needs an i5.
but things will be different if your cpu is OCed but again, it wont match any 4-core cpu.
try to get a C2Q/athlon/phenom/i3 if you can.
and i found a footage of E7500 + GTX 650TI playing unity
https://www.youtube.com/watch?v=vSV1QEQLmNc
keep in mind that 650TI theoritically faster than r7 240, and with E7500 instead of E7400.