What is the shock rating / g-force load of a typical assembled computer?

TLDR: for insurance purposes, we want to alert the recipient of a shipped assembled computer that there might be damage to the components via a shockwatch label. What G-force rating should we use?

We are having problems moving assembled computers via standard shipping services due to rough handling causing damage to the internal components (specifically the GPUs are snapping the PCI-E slots off of the motherboard). Having the shipper provide the outer layer of packaging hasn't helped.

Insurance requires that the unboxing process be documented, but it can be difficult to tell that documentation will be required without opening the packaging, so we want to apply shockwatch labels to the external packaging to alert the recipients.

However, it's not clear what rating we should use. We don't have the equipment to determine this ourselves (nor do we have the desire to destroy thousands of dollars worth of hardware to determine it experimentally). The carriers, obviously, don't make any claims about things like maximum drop height, etc. and so far, the only shock rating information we've found online has been specifically for drives (which haven't experienced damage so far).

We don't need to be very precise about the shock rating, just low enough to catch most of the drops that will cause damage, and high enough to not trigger for every shipped machine. We are also hoping that the presence of a shockwatch label will encourage less cavalier treatment of the package.

Obviously, we are also iterating on our packaging to reduce the likelihood of damage.

After explaining our situation to a sales rep from Shockwatch, he said that typical handling of a 50 lb. package will cause the 25G to trigger every time, and suggested the 50G label.

The lowest.

Seriously - the lowest standard ShockWatch label/sticker is 25G.
A 25G shock is pretty severe (easily enough to dislodge boards, snap backplanes, etc).

You should also label your packaging "FRAGILE" and instruct your recipients to refuse delivery if there is ANY evidence of damage to the box (a crushed corner is often the only outward sign of a 10-foot drop from a distribution center's conveyor belt).