Sometimes during an update a few month ago, my GPU has started working ALOT. I run a NVIDIA Quadro M4000 and have allways played on nighest GFX settings, and no problems. Lately, my GPU has been running at 90-100% during a game, and only if I set it to LOWEST it goes down to 50%. What causes it, and how do I fix it? 
I fear I will have to be the bearer of bad news here. In strict terms the listed GPU does not actually meet the minimum requirements of WoW, so its not that much of a surprise that its laboring under peak load here.
This would also fit the timeline you mentioned: while the minimum requirements have not actually changed over the course of the expansion there have been several structural updates to the game, building on the features/performance all officially supported hardware would be able to deliver.
That is not to say that the video card is ābadā per se, just that its unfortunately not built/intended for gaming purposes - the Nvidia Quadro series is mainly designed for workstation usage, and lacks some features games commonly would tap into for performance optimization.
Yea, I was afraid that was the issue. I was just hoping there was a shortcut or something. Tho, itās fascinating that a 8GB card can make the game run smoothly, but make the GPU works itās a$$ off. Ah well, might aswell start start looking for a replacement. Maybe a 1080Ti or something?
A 1080 (and even more so a TI) would certainly handle WoW with ease, the only suggestion I would make in that regard is to check the power supply unit (PSU) of the computer first.
A Quadro M4000 is listed for 120W draw, while a 1080TI is usually around 180W (this will vary a bit per model) - following the official specs by Nvidia that means at least a 500W PSU is desirable, and you might need more than that if there are a lot of other devices in the computer that draw from the PSU.
I think I have a 925W, need to get down on my knees and check tho. Bought this machine at work (I work with recycled hardware) a year ago, and it was brand new, a HP Z640 MT.
Try reset to default all graphics settings in game menu, restart game and set details again. It happen me also too much burn my RTX2070 Super. Same happen in wow classic. After reset all ok
Yea, tried that and didnāt help Afraid itās what Veadsarias said, my GPU isnāt made for gaming.
There are a lot of GPU benchmarks. You could look at them and compare results. Then you could ask forum what GPUs of your choice players have and how they find WoW. Itās because 1080Ti is quit an expensive card and you would not need to spend that much! You could also be better off selecting something from the Gefore RTX 20xx series as well, like 2060(X), 2070(X). Itās not difficult to select the most expensive card and have a overkill. To some extend you pay for a better card but there is threshold where you start overpaying. Itās harder to find something that matches your demands and yet cost you less.
Your 926W PSU is definitely more than you need as long as you donāt plan to buy another GPUs then you might need to change it to at least 1000W or more. While CPUs with higher cores need more power as well, with Intels on the top, it is GPU which demands the highest wattage.
EDIT. For the time being, you could reduce settings to minimum and even reduce resolution. Itās only temporary but it would help you for the time being.
It can actually be surprisingly tricky to benchmark workstation-GPUs, mainly because (at least in the case of the Quadro series) they often have rather ample raw performance available and depending on the used benchmarking tool can thus punch way above their actual weight class.
To give a (somewhat) flawed analogy here: a bulldozers engine has horsepower ratings that are fairly comparable to the engine in a Formula 1 car, but one of the vehicles still goes a lot faster than the other (on average at leastā¦). 
As such Iād generally recommend to take synthetic benchmark results with a couple grains of salt when it comes to gaming performance. They will not usually translate 1:1, apart from obviously other factors (like memory-type and -clockspeed, CPU, background softwareā¦) further changing the outcome.
A note on that PSU, Yonaz: 900W+ seems rather massive for a regular workstation, and kinda indicates this was meant to be a pretty heavy-duty setup. If the computer was bought second-hand from your workplace maybe you could reach out to the admin there, and check if they have more details/specifications on the installed components or possible even more gaming-suitable hardware available too? There has to be something they wanted to power with that beauty of a PSU, after all. 
Well, benchmarks should not be the absolute true to make oneās decision but they surely are sort of references to compare between GPUs, or to have a good start from somewhere, at least. This is why I said ābenchmarksā. I recommend to consult with other players on a GPU or GPUs of the interest, which I also pointed out. It is not an easy decision to select a proper video card. There are many things to consider, the point with which Iād agree.