You are better off buying a newer and more powerful laptop that does not use an Intel Atom CPU. An example would be the following Acer Aspire E 15 E5-575G-52RJ with a Core i5-6200u CPU and nVidia 940m graphics chip.
https/www.amazon.com/Acer-Laptop-E5-575G-52RJ-GeForce-Windows/dp/B01IHAHGI8/ref=sr_1_3?ie=UTF8&qid=1484932230&sr=8-3&keywords=940mx
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It is possible to attach an eGPU to your current laptop. But it is not an ideal solution especially since your laptop has a weak CPU. You need the following items.
1. EXP GDC V7.0 Beast Laptop External Independent Video Card Dock - You must remove the wireless card from your laptop to insert this adapter. It may or may not fit so do not buy the other necessary items unless this fits. ~ $50
http/www.banggood.com/EXP-GDC-Laptop-External-PCI-E-Graphics-Card-p-934367.html
2. A desktop graphics card. Don't buy something that is too powerful because the mini PCIe port in the laptop only runs at 1x speed which can severely limit a powerful desktop GPU. A desktop PCIe port used for GPUs runs at 16x speed. ~ $75 to $100
3. A power supply to connect to the EXP GDC V7.0 Beast. ~ $40
4. A monitor because laptops do accept video input to the laptop's screen. The one exception I am aware of are some Alienware laptop models. ~ $125 to $150
This is a possible solution, but not very elegant. That is why I recommend you buy a new laptop. Also note that current generation eGPU solutions requires a laptop with a Thunderbolt 3 port like the Razer Core external GPU dock. Laptop with a Thunderbolt 3 port typically cost over $900 to the best of my knowledge. Thunderbolt 3 has very high bandwidth so even a recently released powerful GTX 1080 will not be hindered by that port.