MAMEWorld Forums - Ultimarc - Pinball Cabinet IPAC 2 flipper stutter issue

Hi all,

I have a mini cabinet with an issue that is bugging me for a long time.

setup:

AMD Athlon II X2 Dual Core 3.0GHz
4GB RAM
GeForce GTX 550 Ti 1024MB
Gigabyte 870 A-UD3 Mainboard
I-pac 2

The Problem (using visual pinball):

While pushing the flipperbutton flippers receive a rapid on/off signal and will shoot the ball. The reverse situation happens as well, so not activated by the buttons it will still fire.
Funny thing is that the problem appears mostly (but not only) in the right flipper even after switching wires and connection to the i-pac. In the winipac software you can clearly see the button being activated on/off while being pressed.

Eliminated causes:

OS/software: I checked the issue with XP and W7 - I have the issue on both systems
Wiring : I removed all wires from the i-pac and linked one wire from the I-pac directly to the button. Still the same behavior.
Button: switched buttons - didn't help
Temperature: I added a new more powerful cooler to the CPU - didn't help
I-Pac and USB connection - I bought a new IPAC 2 (latest version) but that didn't help either.

I don't think temperate is the root cause but a high temperature in the cabinet might make it worse. I stopped overclocking more than a year ago and I haven't had the issue for a year. Unfortunately it re-appeared two months ago that is why I added a new CPU cooler. Probably a waste of money, because it didn't help.
I bought the cabinet in 2012 and played 1.5 years without the problem.
Playing the pinball games with a USB keyboard does not result in any stutter.

Possible causes of the issue:

- motherboard
- i-pac
- grounding

Anyone a suggestion how to solve this?

Already presented this question on the vpuniverse forum - see thread here:
http://vpuniverse.com/forums/topic/2055-flipper-stutter/