Buy Laptop, 14 to 15 inch gaming laptop, ASUS, ACER, MSI has a goog cheap one for gaming.

why would you recommend a notebook if he has almost a complete computer which probably outperform almost all cheap notebooks.

@op

if you have patience then just try the xeon on your mainboard. if you want to spend as little as possible then buy a mainboard which works with the xeon.

or you can sell the xeon and choose the most powerful / cheap cpu on the cpu compatible list.

Can you give us the exact model of the motherboard, cpuid/cupz should give you the info.

Here's his mobo. 

http://support.hp.com/us-en/document/c03885123

Pegatron Memphis-S

Time to grab an i7 4790 then, op.

new mainboard is still way cheaper and I'm sure he won't notice much difference between the i7 and xeon(in games). 1333mhz vs 1600mhz ram is almost not noticeable. op should post the gpu he is getting. when spending money than on a better gpu.

New mobo might not be possible in that case. I've seen a lot of mobos where they are physically matx sized, but the cpu heatsink mount screws are non removable from the case itself instead of a separate backplane that bolts through. By doing this they save another part and thus $. If the replacement mobo doesn't have the cpu mounts in the absolute precise same spot, the screwhole mounts will jam against the back of the new board, making fitment a no go, or else they put pressure and risk shorting the board. Otoh, if the heatsink mounting retention bracket is a separate removable piece, then I agree, a $70ish Asrock z97 matx board is gold. Will support 4790k ocing, better usb3 and sata6 performance, 4 ddr3 3000 slots instead of 2 1333 slots, etc. Following that path, simply buying a case and mobo would be still a valid option to consider if OPs case won't take a standard board.

buy a good graphics card and a better psu to power it, should last you a while.

Follow the thread good buddy, op already said those are otw.

Why? because it's just  convenient especially student who always busy gathering data outside or inside school,

for a student laptop is perfect. and the PC spec OP suggesting is not a truly gaming desktop and some middle class laptop have all the spec on it.