For 3 days now I have been trying to figure out why my system is always using 10-15% CPU for system interrupts. I googled and tried every tool I know of - windows performance toolkit, latencymon, process explorer, process monitor. They all indicate that CPU 0 is spiking which I already know, but it doesn't exactly identify what is causing the issue. I might need help to better understand what these tools are saying.
My computer specs are:
ASUS P8B-M motherboard
Intel E3-1230 v1 Xeon CPU (4C8T)
16 GB Crucial DDR-1333 ECC memory
ASUS Nvidia GTX 660 display card (PCI-e x16)
ASUS Xonar DGX sound card (PCI-e x1)
Also used onboard VGA aspeed 16 MB
Also used PNY Nvidia Quadro NVS 420 (PCI-e x16)
Intel SSD 2500 180 GB
Seagate constellation 250 GB
ASUS infineon TPM module
4-port USB 2.0 hub
LG Blueray drive
I have tried removing as many components as possible. I swapped the GTX 660 video card for on-board video and the NVS 420. I removed RAM, removed the sound card, removed the TPM and swapped the SSD with the Seagate. Unplugged the USB hub.
I used the latest BIOS for the motherboard which is 6702. I rolled it back to 6003, did not help. I loaded optimal defaults in BIOS. I changed SATA mode from AHCI and RAID.
I performed a fresh install of both Windows 7 64 and Windows 8.1 U1 64, no additional software installed I have formatted the hard drive on each install case. I also tried booting windows into Safe mode with no network.
Immediately after boot up and login, both have the same issue of showing 10-15% CPU which is the max for one thread in one core. I understand that some .net assemblies run at first boot up but that is not the cause here, the CPU indefinitely stays at that usage level.
I tried turning off hyper-threading and turning of some of the cores. That just spiked the CPU even higher.
I have updated to the latest drivers provided by ASUS. Also tried Driver Easy to get all latest drivers. Also tried disabling some components in device manager such as serial ports and the network ports. Also tried unplugging the network cables. I tried adjusting sound settings and my card doesn't have any enhancement modes that could use up CPU.
I scanned the system for viruses and malware and rootkits. Used ESET Nod32, Malware bytes anti-malware, malware bytes anti-rootkit, and hitmanpro. None of them found anything.
This issue is degrading performance and causing the system to run hotter. But for the life of me, I cannot figure what the problem is.