Hi The Turkish Composer
Welcome here in the family.
"But it's sound is like artificial sound."
Could you give us an sound example? What are the artifacts in you eyes? What kind of speakers do you use?
Here is the pure sound you should have as well. Compare your sound with these examples.
And here is a short example (21. and 26.)when you are using even more articulations just with a bit of reverb from Cubase...
As Bogdan mentioned: A separate sound card would be better than the Realtec. But it should not the reason of a bad sound just with one instrument.
I wish you a lot of fun with your solo strings
Beat Kaufmann