Customs at Suvarnabhumi

I just bought a house in Thailand this year. I'm coming back from the USA next month and need to bring my super computer with me which is a full tower case with dimensions of 57x57x26cm. I'll carry the motherboard and other expensive parts separate in my carry-on so this question entirely pertains to the computer case. It won't fit into a standard luggage check-in bag due to the width so I'm facing a problem where I will have to transport the tower either in its box or some kind of oversize baggage like a sports equipment bag or something. I can say that every single time I've arrived into the USA with a box that I've been inspected by customs.

My concern is if I bring it in a box, Thai customs will want to inspect it. I care less about the fact that they might try to charge me duty for it, thinking it's merchandise because it's definitely used and easy enough to explain that it's not staying in Thailand, but my real concern here is if they inspect the box, they might inspect my luggage too. And I am bringing vitamins/medicine and supplies to last a year and am very worried they'll confiscate the majority of it. I did not have a positive experience with a package I sent to myself a few months ago and it's just over the counter stuff so I want nothing to do with Thai customs when it comes to my luggage.

If I go with a box, is there any kind of luggage-looking cover I could put over the box for the case so that it looks like luggage?

The other idea is to bring the case inside of a sports equipment bag. I'm planning to bring my ice skates with me and could pack some of my hockey equipment too if I bring my sports bag. Is customs likely going to bother me over having a sports equipment bag among my luggage?

Also, has anyone had issues with customs inspecting them if you have several bags? I might need to bring 3 with me on this trip considering the computer case will take up one whole bag. I'm just not sure when they actually bother to inspect baggage / what they look for because I've never had a problem before in my many years of travel.