MasterMace :
First - what is in your X51? There are many configs.
Second - what's your upgrade budget?
Third - do you want to keep the case?
First- 4th Generation Intel® Core™ i3 Processor
4th Generation Intel® Core™ i3 Processor
Windows 8.1
Windows 8.1
6GB Memory
6GB Memory
NVIDIA® GeForce® GTX 745 with 4GB DDR3
NVIDIA® GeForce® GTX 745 with 4GB DDR3
Equipped with 4th Gen Intel® Core™ i3 processor, Windows 8.1 and NVIDIA® GeForce® GTX 745 graphics card. (copy and pasted from website)
Second- 600-700 (can be adjusted if necessary)
Third- I don't want to keep the case