Question Best Cooling Result for MSI R9 390?

[Windyear]

4-year old R9 390 with:
case - Corsair Carbide 200R;
mobo-ASUS Z170-A PRO;
cpu-Intel i5-6600K
cpu fan-CM Hyper 212 Evo;
psu-EVGA SuperNOVA 750 G2;
monitor-ViewSonic XG2401 144hz;

GPU idle temp before treatment=55C;
GPU idel temp after treatment=45C;

Treatment:
switched thermal paste to Innovation cooling graphite thermal pad;
switched GPU fans x2 to Noctua NF-F12 PWM 12V x4; - fan speed set @max=1500 RPM

Is this the best result I can get with this 4-year old GPU? I know this series is known for heating, but is there anything else I can do to improve?

I don't do VR or >2K gaming; max need 1980 122fps;

 

[Windyear]

Just realized one important factor: frequency of monitor. After I switch from 144hz to 60hz, GPU idle temp dropped from 45C to 35C, which should be close to ideal idle temp.