I see. Many advanced games. I am proud of you. For such tasks, you will need a
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Screen. This is what I suggest:
On the low-end, we have a very good Full HD, 23", IPS and LED screen:
http://pcpartpicker.com/part/acer-monitor-umvh6aa003
However, that is way to cheap. So for you son, a monitor which can decimate things at 2560 x 1440 is relevant:
http://pcpartpicker.com/part/asus-monitor-pb278q
Featuring all the things from the last monitor, except with more screen, more resolution, more price, more BALLER.
For extreme competition son, so you can show all that you give no shits, this monitor with its 1ms response time, will do you great honor:
http://pcpartpicker.com/part/viewsonic-monitor-vx2753mhled
All at 27 glorious inches.
If you seeketh the middle road and needth not much real-estate, you can opt for the penthouse suite. It offers more brightness:
http://pcpartpicker.com/part/asus-monitor-vg248qe
Much the same specifications.
Now it is up to you, what is most important.
IPS gives better colors, but makes it difficult to go under 5ms response time.
Resolution gives you detail, which is good if you're a graphics guru.
Inches gives you space, which is good for doing many things at once or impressing thieves.
Price gives you prestige, among those who do not have an income.
Pick!