spambots driving me insane

[TekMaster]

OK so I have a phpBB3 based forum, 3.0.10 to be exact, and long story short; If I see another bot from Lithuania, Ukraine, Sweden, and/or Latvia, I'm seriously going to become bald from pulling out all my hair. It's absolutely ridicules how many spam accounts I delete daily. Seems like the captcha-like GD-3D images I use as anti-spambot countermeasures do no good, the sneaky devs that create the darn things have it all figured out, I'm thinking by means of brute force but I'm not quite sure.
So my question is simple, what's a good antispam question script or mod i can use to stop this before I literally drop technical bombs on these people

Thanks

Edit: OK well I asked a little too soon, I figured it out. lol the newer phpBB3 comes with this function already available unlike older versions.
this can be deleted, sorry about that

 

[Machin3]

There's also that option in phpBB3 i think where you can have members answer a question as an extra means of security when registering.

 

[TekMaster]

Yeah your right, that was what I was trying to figure out, years ago on my older forum phpBB didn't have this feature and you had to edit the script manually. Now they will leave me alone, finally