Need advice on upgrading my Lenovo Legion PC

[Hitpoint]

Hi good people!

I am little on a budget but I would like to buy some used CPU and GPU and upgrade my have a Lenovo Legion Tower PC (Y520T-25IKL) which now has:
intel b250
16gb ram (2400mhz, I think)
GeFroce GTX 1050 ti (4GB)
Intel i3 7100

For CPU I just heard that I need a non-K processor as they cannot be overclocked on my mobo. I am thinking about selling my old CPU and maybe leaving the cooler for the next one.
For GPU I was thinking like gtx 1060 or 1650 / 60 maybe? I also dont know if my mobo can handle those.

What do you suggest? I guess I would need to buy a new PSU too. Currently I have ''LiteOn model no: Ps-5281-02''. Its all on Chinese but it says 264W MAX.

I appreciate all the help I can get as my knowledge is limited when I read the comparisons on Google

I am also on a budget, so I was thinking maybe CPU and GPU till 350 euro, if possible (used ones).


I thank you all!
Have a good one!

Deni

 

[Hitpoint]

My basket at Overclockers UK:

• 1 x AMD Ryzen 3 3100 Quad Core 3.9GHz (Socket AM4) Processor - Retail= £99.95
• 1 x **B Grade** Gigabyte GA-A320M-S2H V2 AMD B350 (Socket AMD4) DDR4 Micro ATX Motherboard= £40.00
• 1 x Kolink Classic Power 500W 80 Plus Bronze Power Supply= £39.95
• 1 x Asus Radeon RX 580 Arez Dual OC 8192MB GDDR5 PCI-Express Graphics Card= £158.99

Total: £349.99 (includes shipping: £11.10)
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Thank you! It means a new mobo too. Does it support m2 ssd?
About the CPU, whats the next better cpu that you can suggest?

 

[Hitpoint]

Okey, then I will measure my motherboard and check if the dimensions are good. I was wondering something else too. Is it okey if I go with gtx 1060 or 1070 and i7 7700? Around 300 euros can be for used i7 and a new 1060, 350-400 with a 1070. What do you think? Is it a better combo than the one in the first answer?