Solved High DPC Latency when Speccy or CPU-Z is running

Hello there people, I recently build a new gaming PC and I now experience DPC Latency issues. The problem only occurs when programs/tools like CPU-Z and Speccy is running.

This is when CPU-Z or Speccy isn't running:


This is when CPU-Z or Speccy is running:


Things I've tried:
- LatencyMon, which however, doesn't detect a problem it seems.
- BIOS Upgrade (Upgrated to 2304 first, then tried 2101)
- Uninstall LAN and sound drivers
- Tried different chipset drivers
- Update Nvidia drivers
- Disable HPET in BIOS
- Tried different anti-virus software
- Tried with and without IRST

My build:
OS: Windows 8.1
CPU: i5 4690k
MB: Asus Maximus VII Ranger (BIOS version 2101)
GPU: MSI GTX 970
RAM Crucial Ballistix Sport 8GB
SSD: Samsung 850 Evo 250GB
HDD: WD Black 1TB
PSU: Cooler Master V550S (550W 80Plus Gold)

I have really no idea what causes this problem. I've just switched from a Asus Sabertooth Z97 Mark2 to a Asus Maximus VII Ranger. I don't remember having this problem on the other motherboard. Could this be hardware related? Drivers? Or maybe a BIOS settings causing this?

Thanks in advance

EDIT: MSI Afterburner doesn't have this problem at least.

The DPC Latency Checker is invalid for Win 8/8.1. They state that on the web site.

The Resplendence Latency Mon is valid.

Programs such a CPU-Z or Speccy aren't run all the time so it really shouldn't be an issue. However my Win 7 system (what I'm on right now) with CPU-Z does have a little Latency spikes. Speccy doesn't cause any. My Win 8.1 install (same hardware - dual boot) shows it is OK with the Resplendence Latency Mon and I have no problems running my recording studio software, so I have to assume it will work just like my Win 7 system.

My system, first without CPU-Z or Speccy running and then with CPU-Z running.

fireberd said:

The DPC Latency Checker is invalid for Win 8/8.1. They state that on the web site.

The Resplendence Latency Mon is valid.

Programs such a CPU-Z or Speccy aren't run all the time so it really shouldn't be an issue. However my Win 7 system (what I'm on right now) with CPU-Z does have a little Latency spikes. Speccy doesn't cause any. My Win 8.1 install (same hardware - dual boot) shows it is OK with the Resplendence Latency Mon and I have no problems running my recording studio software, so I have to assume it will work just like my Win 7 system.

My system, first without CPU-Z or Speccy running and then with CPU-Z running.

View attachment 59044View attachment 59045

Click to expand...

Thank you for the quick response

I guess there is nothing to worry about then. I don't experience any video or audio problems, I was just concerned when I saw the high DPC latency with Speccy running in the background. LatencyMon doesn't report any latency, so I guess I'm alright.
However, I just checked two other Windows 8.1 PCs with DPC Latency Checker and Speccy running. There was no latency issues reported :/ So not all Windows 8.1 based systems have high DPC latency reported by DPC Latency Checker it seems :/

EDIT:
LentencyMon reports a very high kernel timer latency with Speccy or CPU-Z running:


This is when Speccy or CPU-Z is not running:


I'm still not certain if I have a problem or not. I'm not sure if these readings are normal?

Latency Mon shows everything OK so I wouldn't worry about it.

From the DPC Latency Checker web site about Windows 8

Windows 8 Compatibility: The DPC latency utility runs on Windows 8 but does not show correct values. The output suggests that the Windows 8 kernel performs badly and introduces a constant latency of one millisecond, which is not the case in practice. DPCs in the Windows 8 kernel behave identical to Windows 7. The utility produces incorrect results because the implementation of kernel timers has changed in Windows 8, which causes a side effect with the measuring algorithm used by the utility. Thesycon is working on a new version of the DPC latency utility and will make it available on this site as soon as it is finished.

They have been "working on a new version" ever since Windows 8 came out but its never been released. Since Win 8.1 is to be replaced by Win 10 this year I doubt they will ever release a new version.

fireberd said:

Latency Mon shows everything OK so I wouldn't worry about it.

From the DPC Latency Checker web site about Windows 8

Windows 8 Compatibility: The DPC latency utility runs on Windows 8 but does not show correct values. The output suggests that the Windows 8 kernel performs badly and introduces a constant latency of one millisecond, which is not the case in practice. DPCs in the Windows 8 kernel behave identical to Windows 7. The utility produces incorrect results because the implementation of kernel timers has changed in Windows 8, which causes a side effect with the measuring algorithm used by the utility. Thesycon is working on a new version of the DPC latency utility and will make it available on this site as soon as it is finished.

They have been "working on a new version" ever since Windows 8 came out but its never been released. Since Win 8.1 is to be replaced by Win 10 this year I doubt they will ever release a new version.

Click to expand...

I just tested on a third PC and it's almost the same results as mine (high DPC and kernel latency), so I guess I'm alright. Thank you for the help fireberd