Which CPU for 0X8DXD?

Question

Dear experts,

I need any CPU, which fulfils following requirements:

supported by baseboard 0X8DXD
minimum of 6 cores
any single core at least as fast as any single core of the current Intel Xeon W-2125 (4 GHz/ 4.5 GHz Turbo)

I'd like to clarify the specific purpose:

I am running the simulation program Ansys Mechanical, which can only use 4 cores with the current license.
When a solution process is running, Ansys uses 100 % of each core, which is very desirable.
But in doing so, Ansys will inevitably share the utilized cores with any other program (Browser, E-Mail, CAD etc.), slowing each other down.
That's why the recommendation is to have at least 6 cores.
And my guess is, that any single core of any new CPU has to be at least as fast as any single core of the current CPU. Am I correct with this assumption?

So which one could it be?

What alternatives do I have?

Some details of the machine:

OS Name Microsoft Windows 11 Pro for Workstations
System Manufacturer Dell Inc.
System Model Precision 5820 Tower
System Type x64-based PC
System SKU 0738
Processor Intel(R) Xeon(R) W-2125 CPU @ 4.00GHz, 4008 Mhz, 4 Core(s), 4 Logical Processor(s)
BIOS Version/Date Dell Inc. 2.4.0, 06.07.2020
SMBIOS Version 3.2
Embedded Controller Version 255.255
BIOS Mode UEFI
BaseBoard Manufacturer Dell Inc.
BaseBoard Product 0X8DXD
BaseBoard Version A00
Platform Role Enterprise Server

Thanks for the help!

Kind regards,

piknockyou

piknockyou · Accepted Answer

Thank you for your persistence & patience.

I did some more research and according to several user experiences/statements discussed in the Dell Community threads [1, 2, 3, 4, 5] and mentioned on this websites [6, 7, 8] and clearly here, I am able to vaguely conclude the following MB/CPU compatibilities, which were mentioned …

… several times:

02KVM & 0X8DXD & 0TVW7J: W-21XX

06JWJY & 0X30MX: W-22XX

… only once:

0R23KR: W-21XX, W-22XX (up to TDP 140 W?!)

00XNYP: W-22XX [Dell China?]

Since I am not able to find any purchase options for the 06JWJY, I will disregard the W-22XX series.

And even if I did find it, before swapping the whole MB + CPU with effort & money, I believe I should rather consider a new system.

I also found this terrifying user experience, which talks about the throttling of the desired CPU W-2245.

So, let’s forget about this combo.

I think we might get the W-2135 then.

What do you think?

piknockyou · Accepted Answer

I mostly work with CAD software (CATIA) while the CAE software (ANSYS) is solving on full load.

Thank you for your suggestion, but I am afraid it is not feasible, because, even though I have a Notebook, which is CAD ready (Software + License) and even though CAD is quite CPU-light compared to CAE on full load, ...

... when working with huge CAD models, the notebook would lag. This is why I am depending on the CPU/GPU/RAM specs of the Workstation.

... CAD & CAE are communicating by geometry uploads/updates and licenses, which is indispensable.

... using several HIDs/monitors would be inefficient & annoying in regards to space & ergonomics.

I think for now I will settle with the current system, until a full swap is justified, about which I am not certain right now. I think a good test would be, to solve an identical problem with CAE while I am actively working VS being absent and compare the solution times. I might give an update to this thread.

Even though I might not swap the CPU/system, which might seem to be a waste considering the time I spent on this topic, the interaction with you and the research I did, were a valuable lesson. I will take these into consideration in the future.

Thanks!

mazzinia_ · Answer

Hello,

wait for others more knowledgeable to pitch in (and correct me), but that revision of the MB supports only Xeon W first gen , so W-21xx.
a w-2135 would have the same speed as yours, but 6 cores , a 2145 would have 8 cores (and same speed), and finally a 2155 would have 10 cores (and same speed).
I can see 2 more options with more cores, but the max speed is lower ( 5% lower, more or less )

piknockyou · Answer

Thanks for listing those models.

As far as I can see, you listed all Intel Xeon W-2100 series (Skylake) CPUs with 4.5 GHz Turbo Boost:

W-2135 (6 cores; Base Speed: 3.7 GHz)
W-2145 (8 cores; Base Speed: 3.7 Ghz)
W-2155 (10 cores; Base Speed: 3.3 Ghz)

The currently installed W-2125 (4 cores; Base Speed: 4.0 GHz) has a higher Base Speed compared to the W-2135 (6 cores; Base Speed: 3.7 GHz).

But the frequency behaviors of both CPUs seem to have the same profile:

W-2125 (4 cores; Base Speed: 4.0 GHz):

W-2135 (6 cores; Base Speed: 3.7 GHz):

Hypothetically speaking: Please let us assume one single application fully utilizes 4 cores of both CPU models (100 %) with no other task running/interfering. In both cases core 1 & 2 run at 4500 MHz and core 3 & 4 run at 4400 MHz.

Question 1: Is it correct to assume, that with both CPUs the application will perform on the same level ( e.g., in regards to solution time)?

Question 2: Thus, making the lower Base Speed irrelevant in this use case?

For comparison/completeness, the frequency behaviors of the latter two models (click link):

W-2145 (8 cores; Base Speed: 3.7 GHz) / W-2155 (10 cores; Base Speed: 3.3 GHz).

Instead of 4400 MHz, both of the latter CPUs seem to only perform on 4300 Mhz on core 3 & 4. They even perform worse at lower modes and higher active core numbers (irrelevant though in my case).

Question 3: Is it correct to assume, the latter two CPUs are disadvantageous in regards of speed/performance, when the application can only fully utilize 4 cores?

Thank you!

mazzinia_ · Answer

Related to question 1)

Yes it's correct, as long as it keeps on turbo at 100% you would have the same performance you have now. You may want to set the "affinity" of the cores to that specific application so that it runs on core 1/2 for sure.

2) technically yes, since it would be the speed it would fall back in case of overheating.

Worth to note is that the TDP of the 2125 is 120W , while the 2135 is 140W ... so the 2135 will run a bit more hot under full load. Thus as long as the cooling keeps it within reasonable ranges, it will not throttle after a while.

The 2145 would be 2.4% slower as performance on the 4 cores, vs your current setup. Same can be said of the 2155. Since you know the average time for one of your simulations, you can determine how many minutes it would translate into, and if that would be worth the extra free cores (to do something else)

3) yes but only on a 2.4% factor in your specific scenario. You should do the maths based on some of your sims and find out how much time it translates into. Obviously the real question is if you would utilize the extra cores ( compared to the just 2 extra spares ) in the meanwhile

Again, this is a personal opinion.

mazzinia_ · Answer

Ah, but there's another factor

https://www.ansys.com/it-it/blog/hardware-tips-to-accelerate-simulation

it seems Ansys Mechanical uses AVX-512 ... so maybe all that reasoning should be done keeping this in mind, too. Not sure if it's used by default or if you select it in settings. Are you actually using avx-512 during your workload ?

If yes, the 2145 performs better than the 2135, and same can be said for the 2155

piknockyou · Answer

Thank you for your answers.   1. Can you please elaborate on how you calculated 2.4 %? It is not so significant regarding the simulation time, but I do not the see point to 'downgrade' with W-2145 or W-2155.   2. Or would it be an upgrade? I am not sure, if I used the W-2135, I would utilize/max out the 2 extra cores with Chrome/Office/Notes/CATIA, while Ansys runs on 100 % on the 4 other cores.    3. Do you know of any sources of the Frequency Behaviors? I do not know the sources of the Frequency Behaviors provided by WikiChip and if we can 100 % trust them.    4. I do not know and do not think there is any way to change settings regarding the modes (Normal/AVX2/AVX512) in Ansys. I do not even understand what they mean. But I understood from reading some articles (1, 2, 3, 4), that Ansys software products benefit from AVX-512. Is there a way to test this?   FYI: When running a simulation, the task manager shows an utilization of mostly 100 %.  The overall Speed fluctuates between 4.0 to 4.2 GHz. From observing the graphical representation of the utilization, 3 cores seem to run on 100 % all the time and 1 core is fluctuating, but always peaking 100 %:   CPUID Hardware Monitor shows each core fluctuating between 3990 MHz and 4389 MHz at all times: So I am not sure, if all cores run on only 4 GHz each for Ansys. Maybe and the extra load is anything else that runs in the background, maybe not.   5. What makes you say that W-2145 & W-2155 perform better on AVX-512 than the W-2135? Taking the first 4 cores and their utilization from the frequency behaviors of all 3 CPUs into consideration, I would say they all perform the same on average (3900 MHz)? But I do not know enough about CPUs, I am just making this up on the numbers.

mazzinia_ · Answer

I just went for an approximation. 4.400 for core 2/3 vs 4.300 , the 100 megahertz are around 2.27%. so those 2 cores would be that much slower and the sw on them should have that slight performance hit ( but just on them )
2) if it's not significant vs the simulation time, having more than 6 cores ( so more than 2 free cores ) would give more freedom to do parallel tasks with ease
3) no, I don't
4) according to the tables you posted, in "theory" avx 512 would work at lower boost speeds than the ones you shown having, so I'm a bit unsure... either those tables are not right, or ?

5) was based on the tables you posted / linked. the avx512 for the 2135 3900/3900/3900/3900 , the 2145 and 55 are 4000/4000/3800/3800 ... but at the end probably is marginally the same

piknockyou · Answer

1. Thanks for clarifying it is 2.27 % not 2.4 %.

What do you mean by "4.400 for core 2/3"?

Did you mean "4.400 for core 1/2"?

2. I am not sure if it is necessary to have more than 2 extra cores or just a waste of money with a marginal performance drop.

3. I just sent a message to WikiChips Twitter asking for the source for Frequency Behaviour.

5. That's what I guessed.

W-2200 series seems to fit as well, because they also use the Socket LGA 2066.

Will it be compatible with the baseboard 0X8DXD though?

If this is true, I believe the best choice might be the W-2245, because Turbo Boost 2.0 seems to achieve 4.5 GHz on all 8 cores. The higher model numbers show lower Turbo Boost 2.0 values. They would only be feasible, if Turbo Boost 3.0 could achieve at least 4.5 GHz on the 4 active cores.

Do you agree?

mazzinia_ · Answer

I meant your current 2125 runs at 4.400 on cores 2 and 3 , while the other in the comparison has cores 2 and 3 running at 4.300

About the W-22xx , I don't think it will work with that revision of the motherboard you have installed. To have any confirmation you would need to get it from Dell.

There are a few revisions of the motherboard used in a 5820 ( same goes for the 7820 and 7920 ). The initial revision when the units were put on the market around 2017 works only with W-21xx.

The revision put out when they started to offer the option to sell it with a W-22xx ( I think during 2019 ? ) , supports both 21xx and 22xx

piknockyou · Answer

Oh! You started counting from core 0 contrary to the tables, correct?

I called DELL and they could not help me.

I would appreciate a certain answer before I buy the w-2245.

Otherwise I might buy/return.

mazzinia_ · Answer

yep, I went with that 1 2 3 4 ( 5 6 7 8 )

mazzinia_ · Answer

I'm really not managing to find a lot about this specific board revision but

https://www.serverworlds.com/dell-x8dxd-precision-t5820-system-board/

I would not risk, and go with this company stating that it's limited to 21xx cpus

piknockyou · Answer

The link states *Supports Xeon W-21XX Processors* How does this exclude W-22XX? Who knows for sure?

mazzinia_ · Answer

Because the W-22xx is a newer revision made 2 years after the 21xx, and that reseller claims this motherboard revision to be limited to a 21xx.

Mine is an assumption based on the fact that that hardware reseller is limiting its liability by stating the compatibility they are sure of. It may be just playing safe on their side, or they got an answer from dell in such sense, or they actually tested a board with a 22xx and saw it didn't work.

Looking online i saw 3 to 4 different revisions for the 5820 board ( that's used in the xeon variant ), and all 22xx reported using a different revision to the one you have.

If you bought this 5820 in 2017 (you can check with the Service Tag here Product Support | Dell US ), it'll not work with 22xx cpus. It's not a bios issue, some components are slightly upgraded later on, to allow the use of W-22xx

Precision Fixed Workstations

Which CPU for 0X8DXD?

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