Software works weird; Processor 3995WX

offroader10052 · July 21, 2022, 10:02

Hello.

I ask for advice.

I bought an AMD Ryzen Threadripper PRO 3995WX processor and can't use it to its full potential.

Problem:

The same task in Ansys CFX is solved at different speeds.

Each new run of the solution gives a solution at a different speed.

test 1 - 3200 seconds
test 2 - 900 seconds
test 3 - 7000 seconds
test 4 - 1400 seconds

How to achieve the same minimum solution time?

PC specifications
- AMD Ryzen Threadripper PRO 3995WX (64 physical cores, 128 threads);
- 128 GB RAM;
- 512 SSD samsung evo;
- no throttling occurs, temperature 50-55 °C;
- Windows 10 x64;
- Ansys 19.1.

Did not help:

- disable hyper trading

- disable turbo boost

- reinstall win to another copy

- ssd replacement

- Installing another version of Ansys 2021

- installation of all driver and OS updates.

Other programs run fine on this PC with the same repeatable results (benchmarks, video encoding, rendering).

naffrancois · July 21, 2022, 18:45

Can you provide more info on the test case you are running ? How many cells ? Which model ? How many threads are you using ?

offroader10052 · July 22, 2022, 03:32

Quote:

Originally Posted by naffrancois

Can you provide more info on the test case you are running ? How many cells ? Which model ? How many threads are you using ?

2.500.000 cells
I count in CFX
Hydrocyclone of standard design.
Includes oil and water.
I have run successfully this model before on another computer
I tried testing on 4, 10, 12, 16 cores (threads)

flotus1 · July 22, 2022, 04:11

Which memory are you using exactly? How is it populated on the motherboard? Which motherboard? Which version of Windows 10?

offroader10052 · July 22, 2022, 04:29

Quote:

Originally Posted by flotus1

Which memory are you using exactly? How is it populated on the motherboard? Which motherboard? Which version of Windows 10?

DDR4 ECC REG
The motherboard has 8 memory slots.
The processor has 8 memory channels.
I'm using 4 32gb memory slots.
Windows 10 Pro x64

flotus1 · July 22, 2022, 05:01

There should be a memory population guideline in your motherboard manual. Following this is important when using less than 8 DIMMs.
Regardless, you need 8 identical DIMMs to use the full capabilities of this processor. High runtime variance is a direct result of not populating all memory channels. Whether this is the only issue here, I can't tell. But it is definitely a contributing factor.

July 21, 2022, 10:02	Software works weird; Processor 3995WX	#1
offroader10052 New Member Ilya Join Date: Oct 2019 Posts: 16 Rep Power: 7	Hello. I ask for advice. I bought an AMD Ryzen Threadripper PRO 3995WX processor and can't use it to its full potential. Problem: The same task in Ansys CFX is solved at different speeds. Each new run of the solution gives a solution at a different speed. test 1 - 3200 seconds test 2 - 900 seconds test 3 - 7000 seconds test 4 - 1400 seconds How to achieve the same minimum solution time? PC specifications - AMD Ryzen Threadripper PRO 3995WX (64 physical cores, 128 threads); - 128 GB RAM; - 512 SSD samsung evo; - no throttling occurs, temperature 50-55 °C; - Windows 10 x64; - Ansys 19.1. Did not help: - disable hyper trading - disable turbo boost - reinstall win to another copy - ssd replacement - Installing another version of Ansys 2021 - installation of all driver and OS updates. Other programs run fine on this PC with the same repeatable results (benchmarks, video encoding, rendering).

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Inverse and Transient Heat Transfer Problem on commercial software: is it possible?	rogbrito	Main CFD Forum	1	February 19, 2019 03:11
Inverse and Transient Heat Transfer Problem on commercial software: is it possible?	rogbrito	CFX	1	January 29, 2012 18:48
[Other] What software should i learn? - Meshing	Anima	ANSYS Meshing & Geometry	2	November 14, 2011 12:53
New software for simulating laminar flows	HectorRedal	Main CFD Forum	1	April 27, 2011 14:59
Waterhammer software	Andris Skattebo	Main CFD Forum	1	July 18, 1998 22:01

July 21, 2022, 18:45		#2
naffrancois Senior Member Join Date: Oct 2011 Posts: 242 Rep Power: 17	Can you provide more info on the test case you are running ? How many cells ? Which model ? How many threads are you using ?

July 22, 2022, 04:11		#4
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	Which memory are you using exactly? How is it populated on the motherboard? Which motherboard? Which version of Windows 10?

July 22, 2022, 05:01		#6
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	There should be a memory population guideline in your motherboard manual. Following this is important when using less than 8 DIMMs. Regardless, you need 8 identical DIMMs to use the full capabilities of this processor. High runtime variance is a direct result of not populating all memory channels. Whether this is the only issue here, I can't tell. But it is definitely a contributing factor.