Well in medium setting i can play CS-GO and Dota 2(and hell lot of other games in below configuration) on my 10 yr old rig.
Intel Pentium D 3.0 Ghz
2.5GB ram
Radeon HD 4350
128GB SSD harddrive
I am no expert but comparing configuration to mine, you will be well off with a
Intel i3 processor,
Any Radeon better than HD 6K series
Nvidia GTX series
4GB ram.
Having said that i advice you to buy something much better the above configuration. you wont be playing CSGO and Dota 2 in next 2 years, there will be something better just around the corner and you would regret not buying a higher configuration rig to support the new games.
So dont go by my words, I am stating things comparing to my desktop with an approximation. I cannot frankly...