[mothered]

Yes, for the PC (which I don't have) I was going to fill a box with dry ice and send it directly with the return form that they provided me.

It's mostly for the weight because the pc weighs 5kg.

It's concerning.

Due to Its size, signs of tampering will most likely be noticed during Its early stages In transit. Moreover, you'd need to very accurately calculate the dry Ice sublimation time.

if there's a weight check during the package's journey.

There most certainly Is - when checked In at the carrier's depot, and just prior to dispatch. Shipment weights are calculated using a formula as per below.

• Dimensional Weight - self-explanatory, the package length, width and height
  
• Actual Weight - Item and Its packaging
  
• Billable Weight - the greater of the dimensional and actual weight
  

The cost of freight Is calculated thereafter.