Software works weird; Processor 3995WX

offroader10052 · July 21, 2022, 09:02

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, 17:45

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, 02:32

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, 03:11

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

offroader10052 · July 22, 2022, 03:29

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, 04:01

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, 09:02	Software works weird; Processor 3995WX	#1
offroader10052 New Member Ilya Join Date: Oct 2019 Posts: 16 Rep Power: 6	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).

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July 21, 2022, 17:45		#2
naffrancois Senior Member Join Date: Oct 2011 Posts: 239 Rep Power: 16	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, 03:11		#4
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,398 Rep Power: 46	Which memory are you using exactly? How is it populated on the motherboard? Which motherboard? Which version of Windows 10?

July 22, 2022, 04:01		#6
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,398 Rep Power: 46	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.