I've been on other forums with restrictions on new accounts, that e.g. put your threads in moderator review before putting them live. Does Anandtech software not support any of those features?
On popular sites, that can quickly become overwhelming or at least fatiguing for mods, to have to be constantly checking a queue of new account posts to approve them, but I don't know the rate of new account posts per day here, but I'd guess it's quite a few if there is a lot of spam through multiple accounts instead of same account.
I've gotten the impression that the AT forums don't get much if any developer time to fix or improve the site, so any changes might just be wishful thinking, but to me it seems like an opposite strategy might work as well as mod review of new account posts - Instead, set it up so that if a post gets, let's say at least 2 or 3 reports of being spam, THEN the post is automatically removed to a review queue for mods to restore back if not spam, with it an automated one-click restore function.
That's more passive for the mods, and any spam irritating to forum members, you could expect them to report it at a quick enough rate that it's not irritating too many people, since anyone irritated, should be reporting it.
If it's bots doing it, then a more challenging signup than just standard Xenforo might help, but IDK what the signup is even like now, having signed up only so long ago.