You need more information on the MSI mainboard.
The MSI mainboard determines which hardware can be installed.
The Mainboard supports either an Intel CPU or an AMD CPU. Not both.
The mainboard limits the RAM(-memory) used: Either DDR-3 or DDR-4. As DDR-4 is the latest development, prices started high, while DDR-3 was cheap. Currently both are at the same price, it seems.
The power supply is another limitation. If the wattage is low, you cannot obtain some high-end power hungry videocard like the ASUS GeForce GTX 1070 STRIX OC GAMING for 470,- anyway. Besides that: You're getting totally ripped at 470,-. In the moment you buy that, somebody is laughing in his chair at a pool on the Bahamas.
So get us some specs of the mainboard and PSU, then we can tell much better whether the combinations possible at 510 €uro are worth buying.
When my mainboard-CPU combo broke 2 years ago, I had little money and no choice at all. I obtained Mainboard, CPU, CPU-Cooler and Memory for about 390€, if I remember correctly. Considering that you got a mainboard already but need a videocard, 510 € is a sum that can get you some decent hardware.
I regret to have bought only 8 GB of RAM, as high end games like GTA V require 8GB minimum, and if you got a sufficient videocard, those 8GB will lead you to certain limits then. WoW, MW:O or War Thunder are no problem with 8GB though.
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Example:
ASUS GeForce GTX 1050 Ti STRIX OC GAMING 4GB 185,-
Patriot DIMM 16GB DDR4-2800 Kit (depends on MB) 120,-
Intel® Core i5-7500 boxed (depends on MB) 200,-
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505,-