Folding Forum

First question: If I start FAH on CPU the GPU slows down. I get more PPD if I pause the CPU. Is this normal?

Second question: When I pause the CPU, tast manager still shows FAHcore using 15%-20% CPU. Is this related to the first question? Is the CPU essentially having to feed the GPU data or something?

Sorry for the stange questions. Before today I was folding with a i7 960 and a GTX 560ti. Now I'm pulling 2m ppd with a 2070 Super.

Welcome to Folding@Home!

We do not know much about your Computer, you did not post the first 200 lines of your log.

Lets make random guesses anyway. You may have a thermally locked system where the total heat is limited.

Yes, one thread of the CPU loads data into the Graphics subsystem. If you have 6 threads, then one is 16%

i7 960 = 8 threads, it is old enough it will only use SSE2 but you may be able to set it to 4 threads and still drive your new RTX 2070 Super


In advanced Control or FAHcontrol chose Configure, then Slots, then cpu then set it to 4 cpus and save.

Intel ARK shows SSE4.2 for instruction set. Yes I know it's a decade old, I'll be upgrading the Mobo/CPU/RAM next year.
Currently its:
Asus P6x58d-e
Intel i7-960
12GB Kingston DDR3
Nvidia 2070S FE
Corsair RM-850x
Phanteks Enthoo pro
Cooler Master ML360R AIO
Under full load the CPU hits 55C and the GPU 71c

Unibrowser wrote:Intel ARK shows SSE4.2 for instruction set.

This is true, but no current FAH core uses SSE4.2. The current cores use SSE2, AVX, and for Core_a8, AVX2 with FMA3.

I think the underlying GROMACS has more levels, but only these 3 sped up F@H. If F@H more performance in some future core, it could change.

The reason I ask for the log is that it never forgets to mention important parts. (you never mention your OS or the video driver version number for example, even though those are important)

SSE 3 was not tested separately in the past, issues of cross platform usage between Intel and AMD. SSE 4 was tested at one point, the performance improvement over SSE 2 was not sufficient to justify maintaining a separate folding core for F@h usage. SSE 2 was chosen for widest hardware compatibility.

As JimboPalmer mentioned, Core_A7 comes in two versions - SSE2 and AVX. Core_A8 will use SSE2, AVX-256 or AVX2-256 depending on the processor.

Unibrowser wrote:When I pause the CPU, tast manager still shows FAHcore using 15%-20% CPU. Is the CPU essentially having to feed the GPU data or something?

Yes, the GPU cores use a single thread to constantly swap data between main memory and the GPU. The CPU is also used for periodic sanity checks of the GPU to ensure the GPU hasn't screwed up.
The GPU accounts for 12.5% (your task manager will float 12-13%) of your cpu load, the rest of the 15-20% are background tasks.

I tried running FAH on an i7-920 for a short period of time. I wasn't running CPU projects, I was trying different setups to pair with my GTX 1080 Ti. I found the CPU drew full power regardless of load, I didn't run it for long.

aetch wrote:

Unibrowser wrote:When I pause the CPU, tast manager still shows FAHcore using 15%-20% CPU. Is the CPU essentially having to feed the GPU data or something?

Yes, the GPU cores use a single thread to constantly swap data between main memory and the GPU. The CPU is also used for periodic sanity checks of the GPU to ensure the GPU hasn't screwed up.
The GPU accounts for 12.5% (your task manager will float 12-13%) of your cpu load, the rest of the 15-20% are background tasks.

I tried running FAH on an i7-920 for a short period of time. I wasn't running CPU projects, I was trying different setups to pair with my GTX 1080 Ti. I found the CPU drew full power regardless of load, I didn't run it for long.

Yeah it's sitting at 17-20% and only when folding so I am sure it's feeding the GPU what it needs. Before this upgrade, I was running F@H on my i7-960, GTX 560ti and my Synology 918+ running a F@H docker container lol. All 3 of those combined only pulled 34,000 ppd on average, needless to say i'm only running it on the 2070 Super now.

JimboPalmer wrote:

Unibrowser wrote:Intel ARK shows SSE4.2 for instruction set.

This is true, but no current FAH core uses SSE4.2. The current cores use SSE2, AVX, and for Core_a8, AVX2 with FMA3.

I think the underlying GROMACS has more levels, but only these 3 sped up F@H. If F@H more performance in some future core, it could change.

The reason I ask for the log is that it never forgets to mention important parts. (you never mention your OS or the video driver version number for example, even though those are important)

Windows 10 64bit(completely up to date)
Nvidia Driver 457.09

Also, all of the charts I have seen prior to the purchase of the 2070 super shows these cards average 1.6 million ppd. Im getting 2-2.2m ppd. Did I get lucky with a good card? Its only a founders edition and I have not touched an overclock yet (and probably wont)

Unibrowser wrote:First question: If I start FAH on CPU the GPU slows down. I get more PPD if I pause the CPU. Is this normal?

Second question: When I pause the CPU, tast manager still shows FAHcore using 15%-20% CPU. Is this related to the first question? Is the CPU essentially having to feed the GPU data or something?

Sorry for the stange questions. Before today I was folding with a i7 960 and a GTX 560ti. Now I'm pulling 2m ppd with a 2070 Super.

Each GPU does require CPU resources to feed data to it. By default, (when FAH configures itself) it leaves one CPU unused (from it's perspective) for each GPU that needs data fed to it, so yes it's normal. If you override that default, you will see a loss in GPU performance. It also depends somewhat on the manufacturer of the GPU's chip. has

Your i7 960 has 4 independent CPU cores, grouped in pairs and reported as 8 hyperthreaded GPUs. Your GTX 560ti really needs the dedicated resources of one thread. FAHCore_A7 allocates a second free thread, too. If you fill those two threads with heavy processing, from another task, the GPU will certainly run slower.

bruce wrote:

Unibrowser wrote:First question: If I start FAH on CPU the GPU slows down. I get more PPD if I pause the CPU. Is this normal?

Second question: When I pause the CPU, tast manager still shows FAHcore using 15%-20% CPU. Is this related to the first question? Is the CPU essentially having to feed the GPU data or something?

Sorry for the stange questions. Before today I was folding with a i7 960 and a GTX 560ti. Now I'm pulling 2m ppd with a 2070 Super.

Each GPU does require CPU resources to feed data to it. By default, (when FAH configures itself) it leaves one CPU unused (from it's perspective) for each GPU that needs data fed to it, so yes it's normal. If you override that default, you will see a loss in GPU performance. It also depends somewhat on the manufacturer of the GPU's chip. has

Your i7 960 has 4 independent CPU cores, grouped in pairs and reported as 8 hyperthreaded GPUs. Your GTX 560ti really needs the dedicated resources of one thread. FAHCore_A7 allocates a second free thread, too. If you fill those two threads with heavy processing, from another task, the GPU will certainly run slower.

Awesome! I appreciate the info. I have since completely paused CPU because the GPU ppd loss to CPU ppd gain, is a net loss lol.

Unibrowser wrote: Awesome! I appreciate the info. I have since completely paused CPU because the GPU ppd loss to CPU ppd gain, is a net loss lol.

That may be overkill, but it depends on what's happening on your system.

what I do is: WIth all FAH slot paused, I look at how many CPUs are typically busy. Out of 8 threads, that's an non-fah passive activity of about 25%, that's two threads. Adding one GPU slot can be another 12% so there are about 5 free threads. I would probably configure a single CPU slot to use 4 threads as it's unlikely to compete with the CPU processing to suppy the GPU with data.

In addition to what bruce mentioned, you can allocate specific CPUs to processes using CPU affinity which can be implemented via third party solutions. I have used Process Lasso (https://bitsum.com/) and if you know what you're doing, it works really well. Just note that incorrectly configuring can result in your system being unresponsive.