after I change my CPU and mainboard (which the vga/lan/sound is onboard), do I have to reinstall the routeros or i should work fine?
thanks

don't change the HDD and you'll be fine. HDD is all that matters

What you could run into is that interfaces have to reconfigured or re-named (especially the onboard lan), but that should be all...

thank you guys, I'm going to roof top now

because of an hardware change (which i tested several times) I found out that I had to reconfigure / set the new interface on the following items:

1) If you bridge , include the new interface on the bridge. INTERFACES -> settings -> bridge
2) enable the ip settings on the new interface. IP -> ADDRESSES. You'll see an ip range with an unknown interface. just click on it en select the new interface
3) If you use Queues in the queue-tree, set the right interface on these queues.
4) I also found out (just 1 time) that you'll have to clear the arp table manually on other MT's , but theoreticaly this isn't necessary

it's probably because the MAC addresses change and the interface names can get lost. yes, you should also be aware of this fact