Hi LiMpIch and Welcome to ROG. This is taken from an article I discovered.

How to trace and fix DPC latency

First of all, any action you take is at your own risk, don't do anything you aren't sure of, always do your research first before any actions!

Begin with the basics and update your Windows and hardware drivers then properly clean up your PC
Use the tool in the link below to trace DPC delay precisely into single driver files: http://www.resplendence.com/latencymon
Disable High Precision Event Timer (HPET) in BIOS
http://forums.guru3d.com/showpost.php?p=3770113&postcount=2

* Note: If you're using an Asus motherboard the HPET is enforced, so skip this fix and proceed to the one below.

Timer Resolution (this little tool decreases my DPC latency quite nicely)
TimerResolution is an application to change the resolution of the default windows timer.
The standard timer on Windows 7 can vary between 10 and 25 milliseconds. Therefore if your code uses a timer or sleep value less than the timer resolution on your system you won’t be getting the results you expect. http://www.lucashale.com/timer-resolution/

ACPI Power Management: Balanced power modes etc. may cause CPU throttling which slows down your CPU so set all your power management options to full performance and look into how you can disable CPU throttling on BIOS.

Also, check into the link below for more info about ACPI.sys
http://www.techtalkz.com/windows-xp/10281-acpi-sys-causing-very-high-cpu-usage.html#post42863

Networking devices are often known to cause DPC lag,

Disable WiFi/networking/LAN devices one at a time to see if it has any effect, there might be a hardware conflict causing latency.

Unplug different devices you have plugged into your system, even something minor like an USB mouse plugged into a USB extender may be causing your latency to increase
It is quite common for different video card drivers and even BIOS drivers to act up and give out different performance, you might want to try out various drivers for your video card and updating the latest BIOS drivers.

Also review this thread: http://www.overclock.net/t/1441383/dpc-latency-constant-stutter-all-games-affected-fps-ok

Hope this helps. MM