Upgrading Lenovo Y900-34ISZ

[Kiw]

Budget (including currency): 200 - 250 euros maybe? It's kinda flexible.

Country: Estonia

Games, programs or workloads that it will be used for: Escape From Tarkov, League, Rust, maybe streaming.

Other details (existing parts lists, whether any peripherals are needed, what you're upgrading from, when you're going to buy, what resolution and refresh rate you want to play at, etc): I have a i7700k in it with a GTX 1080 and a single stick of 16GB of RAM running at 2400 (M378A2K43CB1-CRC)  and I've got a LENOVO SKYBAY (U3E1) MOBO.

I'd like to upgrade my ram and I'd like to add another cooler to the front of it, it's got 2 slots at the front of which 1 already has a cooler(I have no idea how big it is tho, can't find any specifics on it, if needed I can take a picture of it). I want to know if I should just buy another stick of the same ram or should I actually buy completely new ram.
Any other tips are welcome.

Yes I know pre-builts are terrible but at the time of the purchase, there weren't many parts available in Estonia to build a pc.

 

[Kiw]

Also it would be awesome if someone could suggest a 144hz monitor that's semi cheap, if possible from this site https://www.hinnavaatlus.ee/products/Arvutikomponendid/Monitorid/?sort=min_price&page=1 but it's in Estonian so it might be a hassle.