Satbillity Testing while Multitasking

[xSOSxHawkens]

Hello,

I have been using the firestrike and skydiver stress test runs to help establish overclocks on my other PC's. I have been planning to do so with my main rig, but every time I sit down and think to do it I also want to do soemthing else. Even if I cant game I want to be able to watch netflix or sometihng.

With other systems it was no big deal, I could use my main rig while they tested. But the main rig is the one I use and put simply I dont want it to be down while testing.

I figured I had a sollution. I watched CPU usage during stressing and saw it was very low, that the stress was all GOU bound. So having an i7-4790K with intel HD 4k graphics, I simply swapped my HDMI running to the TV off my 960 and into the Intel HD.

My thought process was that I could have the Stress test run exclusivly on the 960 displayed on my 1080p screen, while I watched netflix in a seperate browser running on aseperate screen being pushed by my IGP exclusivly. My CPU has an overclock to 4.8Ghz, and the stress test uses less than 1/4 that so I figured that the 75% spare CPU power, with multiple free gigs of ram all being pushed by the Intel HD4000 could play 720p netflix while the stress test was running.

Apparently I was wrong.

Running netflix on the IGP with firestrike on the 960, despite having ovcer 8GB of free ram and despite being below 50% cpu usage and I still see dropped frames in both the netflix stream and the stress testing, with unreliable and unrepeatble stress runs.


My question is why? I can use the same setup to play BF1 wth the GPU maxed and CPU well over 50% and have the second screen play 1080p youtube without either the game or the youtube stuttering, as long as I run each screen on its own display adapter.

Why can I do that but not run the stress testing. What unseen and unreported part of my system is being saturated to such a point that its unable to play smooth? And why does 3Dmark saturate that when tripple AAA titles with high GPU and CPU usage simultaniously dont see the same hit?


Any ideas?

[[AU] Tabris:DarkPeace]

Because with HyperThreading enabled the logical cores share limited CPU resources, creating contention when above "50%" CPU usage.

The "50%" just means that the CPU is 'at load' and anything above this indicates that the HyperThreading is actually gaining you some performance, even though it might feel like otherwise due to the contention of shared CPU resources.

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[xSOSxHawkens]

Originally posted by Scott (Australia, USA):

Because with HyperThreading enabled the logical cores share limited CPU resources, creating contention when above "50%" CPU usage.

The "50%" just means that the CPU is 'at load' and anything above this indicates that the HyperThreading is actually gaining you some performance, even though it might feel like otherwise due to the contention of shared CPU resources.

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I am well aware of that.

Thats my whole point...

If I can play BF1 which loads the cpu to 50%+ with the game engine alone without issue. Despite overall usage being at 60-80% once you add in overhead and the netflix tab in the broswer and discord etc. Again without issue...

Why cant I do the same with only ~30% or less cpu usage when running the Stress Test. 3dmark only uses a single thread, aka ~13% of an i7 or a full core at bore if its hyperthreaded second thread is not in use...

EDIT: Figured I would add for clarity that I have been working with HT since the S478 P4's so I am pretty knowledgable about its functioning. As for what I have tried. Disabling HT in the bios makes no difference. Neither does locking affinity in windows to a sinle thread (thread 0) or a single core (threads 0, 1). Stttering either way. Even isolating the stress to two cores and the browser to two cores (4 threads each).

Again, note that I can run games like this with no issue, and the CPU, and both GPU's have no issues with the stress test alone.

I just cant figure out why 3dmark is the only heavy 3d program I cannot run without issue while also using my IGP without issue.

[UL_Jarnis]

I'm not sure what components Netflix playback stresses. Memory bandwidth?

3DMark is not designed to operate in multitasking with other apps - it uses exclusive full screen mode on the main monitor and this may cause other applications that try to use other screens (even on another GPU) to run into performance issues. In short, DirectX exclusive full screen mode is intended to be... exclusive. This is done to ensure repeatable scoring.

Of course if all you want to do is to run stress testing simultaneously, you could just run custom run of one game test in loop in windowed mode. This should affect other applications far less.

[xSOSxHawkens]

Originally posted by FM_Jarnis:

I'm not sure what components Netflix playback stresses. Memory bandwidth?

3DMark is not designed to operate in multitasking with other apps - it uses exclusive full screen mode on the main monitor and this may cause other applications that try to use other screens (even on another GPU) to run into performance issues. In short, DirectX exclusive full screen mode is intended to be... exclusive. This is done to ensure repeatable scoring.

Of course if all you want to do is to run stress testing simultaneously, you could just run custom run of one game test in loop in windowed mode. This should affect other applications far less.

Thanks for the reply. I was just curious what the cause might have been :)