If a WU is assigned X cores, will x+1..n change anything?

[BP2020]

My PC older, but the CPU (i5-2500k - 3,3 Ghz) is burnt-in. Still, I want to keep it below 70C (TjMax is 98, but I consider >70C will reduce the lifespan of my CPU, that's just is my opinion and I will act accordingly), which is the case at either medium or high folding power. Yet, as the weather is getting warmer here, and this is getting close to my tolerance level with 3 cores out of 4 total, I decided to set the folding power to medium (2 cores in my case, as my configuration is by default i.e. -1), which provides me with a better margin for safety, especially for unattended folding (I'm the cautious type).

I did that — before — getting any WU assigned. After a WU was assigned and this had been folding for some time, I thought I would increase the folding power to high (+1 core) thinking that would decrease the time to completion. It seemingly did not as the estimated time remained the same (I waited a few minutesg). The only perceivable impact was the temp getting higher...

I can't imagine comparing the time for a WU to complete with 2 and 3 cores as no WU is exactly the same. Do you think my assessment using the estimated time makes sense. If so, am I right in concluding that once a WU has been assigned for x cores (or threads as people often say), x+1..n will not decrease folding time/make this any faster (I understand the point is moot for most users with a fixed number of threads but the default configuration for new donors will be -1 for the CPU slot)? Is it just because in my case it's x+1 i.e would x+10 have made a difference? Is that about WUs being customized for threads configured, or that's just the client behaviour? This is basically a follow-up to another question and some answers provided then...

[PantherX]

When the CPU is downloaded, it is based on what the client requested. Say it was 4 CPUs. When folding, you can change in-flight the 4 CPUs to any value that's less than 4. However, you can't change the value to anything higher than 4.

When the WU is downloaded, the highest value of CPU is fixed and can't be changed. However, the value can be lowered as long as it doesn't encounter an issue with a bad number. If it does, the WU might be dumped if there's verification failure.

In your case, did you want for the percentage to increase by 3%? It calculates the ETA based on the last 3% so it might take a while for it to be updated.

[BP2020]

Thanks, I should have waited longer indeed and therefore my assessment was inaccurate. I increased by one thread, and was watching the ETA it it was going down sort of like a clock in the Advanced Control and after 2% there was a 10 mins drop and then after 3% another 6 mins. So I consider there is no doubt it will decrease folding time/make it faster...

So I'm not sure what to make of your fist statement in terms of not being able to change the value beyond what was initially set. You seem to be saying that if a CPU WU is assigned for a number of threads, it stays a WU for that number of threads. Then I understand an extra thread works towards one of those threads i.e. a WU is assigned for a CPU slot of 2 threads, then an extra thread will come in support of those 2 in some way, and not "convert" this to a 3-threaded WU, if that makes any sense. It's beyond me. I'm satisfied that increasing the count makes it faster. Thanks again!

[PantherX]

In your case, my best guess would be that you had a 4 CPU request but when assigned a WU (which has a limit of 4 CPUs), your client ran it with 2 CPUs. When you changed the value, it became 3 CPUs. Thus, the limit of 4 CPUs was never crossed and also explains your situation. Do note that the requested CPUs value can always be equal to or lower than the number of CPUs folding the WU.

[Konadreamer]

Yeah, I get it that you're concerned about CPU heat. One way you can run all of your cores but still decrease the heating is to limit frequency (underclock). You don't have to do that in the BIOS you can simply do it from your power plan settings. Goto "Power Options" from the control panel. It will show you your current power plan. Click on "Change plan settings". On this page you will see another link for "Change advanced power settings". Click on that. Then you'll get a pop up with a bunch of other settings, but the one you want is under "Processor power management". Open up that tree and you'll see a setting for "Maximum processor state". This is where you can manipulate the core frequency by changing the value (0-100%). For example, if I punch in "99%", my i7-8750H will throttle down from 3.8Ghz to 2.2 Ghz. I can further reduce it to 1.9Ghz by punching in "90%". So depending on your processor specs and how it regulates its frequency clocking, this is an easy way to drop the frequency and reduce your heating.

[MeeLee]

I remember increasing the CPU count, but it didn't really speed up folding.
Eg; I set FAH to 2 cores, it downloads a WU. I then change the CPU count to 4 cores. The CPU will run slightly hotter, as the 2 threads now get spread over 4 cores (extra L-Cache is being utilized).
Meanwhile my WU doesn't speed up proportionally to the increased core count. My cores also aren't 100% load anymore. More like switching between 80% and 23% or so.
I could increase core count, and finish the WU. Upon completion, a new WU would be loaded, and now all my 4 cores are 100% active.

[bruce]

I remember increasing the CPU count, but it didn't really speed up folding.

Actually, what you observed was that it didn't immediately change the estimated speed or completion time. The estimate was still based on the recent rate of progress, which did not change. As the speed has now increased, there will be new data on which a new estimate can be based. but that doesn't happen immediately.

[uyaem]

Also, was it not impossible for the client to use more cores than were configured when downloading the WU?

[PantherX]

That's correct, the maximum number of CPUs a WU can run at is dictated when it is downloaded. However, if your slider was at Full when the Slot downloaded the WU, it will be at that value. You can later change the slider and number of CPUs but it will not be higher than what the WU was originally downloaded at.