[triggermuch]

Im not very well versed in this.

Fair enough.

My understanding is, you use the regular return label, and fill the box with dry ice as it will sublimate before arrival.

That Is correct.

If the original package was 5.5 pounds.

It's the "Item" and not the package.

I doubt the GPU per se, will be anywhere near that weight.

How many pounds of dry ice would I need to use?

It depends on atmospheric conditions, transit and storage time.

All I know is that it'd need to weight atleast 5.5 pounds at the first scan/weight check.

As said, I don't believe your GPU Is the said weight.

The AMD Radeon RX 6600 Is around 1.6 pounds (725 grams), so I don't see how yours can be such a huge variance. 

When is the 1st weight check?

Depends who's servicing the delivery.

Postal services take the weight at the counter, while carriers record It the moment It reaches their depot.

Might be hard to believe but GPU's have increased pretty drastically in size/weight. The rtx3080ti being about 4 inches longer than the rx6600 you mentioned. But yes, the weight varies by brand - I've seen 4.4,4.7, 5.2 etc. Wont know until I receive one myself.

Do you box yourself? For this scenario lets pretend that it ends up weighing 4.5 pounds. Through UPS, in minnesota weather conditions, how many pounds of dry ice would you consider?