[ALBATTROSS]

Hi,

I had a computer with four cores and it was very slow for my simulation so I got a new computer with Core i7- 8700 k CPU and 32 GB of RAM however, the simulation is still slow. After being slow in serial mode I set the simulation to parallel processing with 12 processors, however it is still running at 1 GHz speed I changed the processors to 16 from FLUENT startup and I couldn't see any difference while I expect something else because this CPU only has 12 logical processors. I need my simulation to be done faster can you please help me with how can I use the maximum capacity of this CPU?
I attached a screenshot of the performance of the 12 CPUs below:

[GregCFD]

The CPU dropping back to 0.86 GHz while under load looks like thermal throttling too me. If you can, I would double check to make sure the fan is properly mounted and running. In my computer the CPU fan sometimes sticks and I get a similar slowdown from anything more intensive than 5 minutes on the desktop.

[Xtreme]

Did You tried some free software like CPU core parking manager (Park Control?)

[flotus1]

There could be a multitude of issues here:

1) First of all, your CPU has 6 physical cores. So while debugging your system with Fluent as a benchmark do not use more than 6 threads. Later when you know your system works correctly you can try if 12 threads give slightly better results.

2) Software settings. In the bios and/or in windows power management the CPU could be locked to a low frequency.

3) Thermal issues. The CPU might be thermal throttling due to inadequate/faulty cooling. Install a tool like HWInfo that gives you access to thermal sensor data.

4) Memory bottleneck. Execution speed might be severely limited by slow and/or single-channel memory. I assume you have 2 sticks of RAM, are they in the right slots for dual-channel? What memory frequency did you get?

5) I/O bottleneck. Maybe you are running a transient simulation that writes lots of data frequently to a slow disk?

A simpler CPU benchmark with known results to compare against will also come in handy while debugging your system. Cinebench for example.

[ALBATTROSS]

Originally Posted by GregCFD

The CPU dropping back to 0.86 GHz while under load looks like thermal throttling too me. If you can, I would double check to make sure the fan is properly mounted and running. In my computer the CPU fan sometimes sticks and I get a similar slowdown from anything more intensive than 5 minutes on the desktop.

Thank you for your response I checked fans are working. I have another computer with the same parts and I assembled both of them myself the other one uses 50 % of CPU and it has an industrial fan. it seems that the one with better case cooler is more efficient so it may be an over heating problem what's your suggestion?

[ALBATTROSS]

Originally Posted by flotus1

There could be a multitude of issues here:

1) First of all, your CPU has 6 physical cores. So while debugging your system with Fluent as a benchmark do not use more than 6 threads. Later when you know your system works correctly you can try if 12 threads give slightly better results.

2) Software settings. In the bios and/or in windows power management the CPU could be locked to a low frequency.

3) Thermal issues. The CPU might be thermal throttling due to inadequate/faulty cooling. Install a tool like HWInfo that gives you access to thermal sensor data.

4) Memory bottleneck. Execution speed might be severely limited by slow and/or single-channel memory. I assume you have 2 sticks of RAM, are they in the right slots for dual-channel? What memory frequency did you get?

5) I/O bottleneck. Maybe you are running a transient simulation that writes lots of data frequently to a slow disk?

A simpler CPU benchmark with known results to compare against will also come in handy while debugging your system. Cinebench for example.

Hi Alex,

1) Thanks for the advice
2) The CPU usage is set to 100%
3) I attached the temperature sensor results. I got these result while no background application was running and it goes to 100 C when I'm running the simulation. It is interesting that the air leaving the case is cool and the intake and blowing fans are working ( CPU cooler radiator at front the case- intake and case fan at the back-exhaust).
4) Yes I have 2x 16 GB RAM I followed the instruction of MOBO manual for slots.
5) I'm running transient simulation on SSD.

6) The benchmark result is not good at all:
https://www.userbenchmark.com/UserRun/15305268

Your suggestions were very helpful. What's your opinion after these results?

[flotus1]

HWInfo has logged thermal throttling events and the temperatures are way too high.
Definitely an issue with CPU cooling. Which cooler are you using? You should probably check for proper installation of the CPU cooler and thermal paste application again. And don't take this the wrong way, but you would not be the first one to forget peeling off that plastic protection foil from the bottom of the cooler