I brought an 8 bay Synology from US to Europe. Pulled the drive and stuck them into a Pelican case and carried it by hand, and the Synology went into the suitcase. No one weighed it. TSA didn't even bat an eye.

For my PC I kept the mobo, ram, CPU and drive. These were all still attached and in the motherboard's original box. Left the case and PSU an CPU cooler. GPU went separately into an anti-static bag.

In my 20 years of travel, flying out of the US, no on gives a shit how much the carry on weighed as long as it fit in the sizing thing. In Europe they are more strict about the weights of carry on bags and can enforce it, but in my experience as long as it doesn't look ridiculous they don't usually hassle you.

If I have to do this again, I'd seriously consider switching to one of those new Asustor Flashstor 6 or 12 devices. I'm tired of dealing with HDs.