Weird color artefacting with HD5450 on Sierra

[Antarès23]

Hi !

So I installed Sierra on my HTPC and I have some weird color artefacting, even tho there's graphics acceleration. (see the picture)

How can I fix this ? Here's my EFI folder, in case there's anything wrong with that : https://drive.google.com/file/d/1-407S-g5x997VAzZilF5IIHWEDrCbUsK/view?usp=sharing

HP Elite 8300

Core i5 3570

8GB RAM

Radeon HD 5450

Sierra 10.12.6

Clover r5070

 

 

Thanks.