New rig crashing as soon as I try to 5-box

[Kalros]

Hey guys, just got a brand new computer and was pretty excited to try 5-boxing WoW again, but unfortunately, as soon as I pull up 5 windows (Using ISBoxer), my system crashes. Before I lose everything I can quickly see a message about my "graphics driver has stopped responding", something to that effect. My system spec is as follows:

Processor: Core i7-6700 @ 4.00 GHz
RAM: 64 GB
OS: Windows 10
Graphics Card: Radeon R9 380, 4GB GDDR5

All drivers are up-to-date. I would think that this system would kick the shit out of any WoW multiboxing I could throw at it, since it blows away my last PC and I was boxing just fine on that one. There's got to be some sort of issue/setting that I'm missing.

Also, I was 6-boxing EverQuest just fine on this new rig last week.

Also, no add-ons for any character are active except ISBoxer

Update: I logged into the individual characters through ISBoxer and lowered their graphics settings. Being a fresh WoW install, they defaulted each window to max graphical settings for everything. Seems to be working now.

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Maybe not. Took the team into BWD and it crashed again

So I went in and lowered EVERY window's graphics to the lowest possible setting, and as soon as I start taking the elevator down in Blackwing Descent, I still crash. I'm stumped at this point. This makes no sense to me.