[Mojave] MSI 580 Armor - Mouse Lag

[disvar]

PROBLEM:
The mouse cursor is lagging in random patterns, like every 5-10 seconds.
I already tried changing the peripheral (both wired).

MY BUILD:
H77N-WiFi Gigabyte
i3-3225 (Ivy Bridge)
MSI RX 580 OC Armor 8 GB
Atheros 9280 WIFI (not using it atm, just ethernet)

2560x1440 Primary Monitor with DVI-D only input.
1920x1080 Secondary Display with HDMI.

INSTALLATION:
BEFORE:
The system was working well before my previous GPU fried, so I had to change it.
I got the 580 thinking it really was OOB...but I noticed this problem with my old settings. I was using Sierra.
Everything else was going perfect, just a couple usb not working.
AFTER:
Clean install using Clover 5103 and Mojave 10.14.6.
All different SSD disks.

All kext were downloaded this week and placed in /Other:
-VirtualSMC
-Realtek8111
-AppleALC
-USBInjectAll
-WEG
-Lilu

UEFI:
-ApfsDriverLoader.efi
-AptioMemoryFix.efi
-HFSPlus.efi

Config.plist: vanilla Ivy Bridge with iMac13,2 definition.

BIOS: Primary Display is PEG and iGPU is disabled.

So, what to do now?

 

[disvar]

I tried upgrading to Clover 5115. No change.
I read something on the forum about monitors and cables, but I don't have many choices:
-I have no menu on the display - it's a Korean Crossover 27QP
-Can't try it HDMI or DP cables to DVI - passive converter cannot sustain 1440p resolution

Is there something else I should evaluate? Could it be defective RAM?

 

[disvar]

Tried changing monitor with a smaller 1050p and it does not show any defect.
I cannot afford to buy a new 27" just for this little bug.
Why does it show with this Gpu?