Your second theory is correct. The first sale doctrine does not apply when the initial copy was not lawfully made, at least under the US Copyright Act. Without that exception, section 501 imposes strict liability for infringement. It doesn't require that the plaintiff allege or prove knowledge or bad faith.
The reason for this might be more obvious in the context of something more obviously infringing, such as bootleg DVD movies. A plaintiff can hold the reseller of the bootleg DVDs liable just as it could the manufacturer. That's desirable since the manufacturer could be judgement-proof (e.g., fly by night company). And we wouldn't want the copyright owner to have to prove that the reseller knew the DVDs were bootlegs.
In the case of distributing Intel CPUs, the principle isn't as obviously applicable as it is to bootleg DVDs, but it still applies. So, the resellers could be held liable for copyright infringment as well.
That being said, since Intel isn't a fly-by-night operation like a manufacturer of bootleg DVDs, the copyright owner can just go after Intel directly.
The reason for this might be more obvious in the context of something more obviously infringing, such as bootleg DVD movies. A plaintiff can hold the reseller of the bootleg DVDs liable just as it could the manufacturer. That's desirable since the manufacturer could be judgement-proof (e.g., fly by night company). And we wouldn't want the copyright owner to have to prove that the reseller knew the DVDs were bootlegs.
In the case of distributing Intel CPUs, the principle isn't as obviously applicable as it is to bootleg DVDs, but it still applies. So, the resellers could be held liable for copyright infringment as well.
That being said, since Intel isn't a fly-by-night operation like a manufacturer of bootleg DVDs, the copyright owner can just go after Intel directly.