The problem with running ethernet over longer distances is not just signal loss, but noise and cross talk as well.
Amping up the signal will only increase the problem of noise and cross talk.
I agree with skip555 above, fiber is the only real reliable alternative for a run of this length for "wired" connectivity.
You can look into a wireless connection to link your two ends together. Install an access point with an external antenna at the router side, and install an external wireless adapter at the computer side with an external antenna.
Works fine, lasts a long time. Paint it grey, it lasts forever.