Question TR 24 Core 3960X, 32 Core 3970X: 280W? (16 Core downgrade)

[Kedas]

Buying an 24core on TRX40 and turning it in an 16 core to drop power is probably a waste of money, but can it be done? What would the power and performance be compared to an 16 core 3950X on AM4?
I assume the gamer mode setting would take care of less active cores.

Any guesses on cooling 280W with an air cooler? 250W was just acceptable.

The only settings I need from AMD for TR is enter your max power (Watt) and enter the max number of cores to be used, on the fly if possible, then I'm happy.

 

[Kocicak]

I would wait for 3 more days for the reviews. You will see what the actual power consumption of the CPU is, how is it configurable etc.

 

[uzzi38]

You can do that in Ryzen Master without an issue, and probably from the BIOS as well. You can disable cores and set the PPT limit you'd like (which is the maximum amount of power the cores can draw from the socket).

I think 280W is just right at the limit of what you'd want on an air cooler, maybe slightly too high, but dropping PPT to about 250-260W would work just fine with a good cooler.

 

[moinmoin]

Performance should be comparable. Power usage will be higher due to the bigger IOD (how much with the latest Threadripper is to be seen, Epyc pretty much has 4 time the IO of Ryzen and power usage of the uncore is respectively around that as well, most notable at idle).

 

[Markfw]

Buying an 24core on TRX40 and turning it in an 16 core to drop power is probably a waste of money, but can it be done? What would the power and performance be compared to an 16 core 3950X on AM4?
I assume the gamer mode setting would take care of less active cores.

Any guesses on cooling 280W with an air cooler? 250W was just acceptable.

The only settings I need from AMD for TR is enter your max power (Watt) and enter the max number of cores to be used, on the fly if possible, then I'm happy.

Yes, its a total waste. If you are worried about power and want 16 cores, get the less expensive 3950x, its almost 1/2 the cost.

 

[Kedas]

Yes, its a total waste. If you are worried about power and want 16 cores, get the less expensive 3950x, its almost 1/2 the cost.

You seem to forget that my applications with 2 memory channels take about 33% longer compared to 4 channels.

 

[Topweasel]

You seem to forget that my applications with 2 memory channels take about 33% longer compared to 4 channels.

Then why not leave it at 24c?

 

[Markfw]

You seem to forget that my applications with 2 memory channels take about 33% longer compared to 4 channels.

Then why disable 8 cores ? If you need the memory speed, I am sure the cores will also help.

 

[Kedas]

Then why not leave it at 24c?

Because I don't want to deal with 280W on air since I don't do liquid.
But maybe this PTT setting will do the trick.

 

[Topweasel]

Because I don't want to deal with 280W on air since I don't do liquid.
But maybe this PTT setting will do the trick.

Okay but taking 33% of the cores would seem to be as bad as the memory hit. Least the other one you need less memory and a CPU half the price.

 

[scannall]

Because I don't want to deal with 280W on air since I don't do liquid.
But maybe this PTT setting will do the trick.

That should do the trick just fine. I doubt that would drop the clocks by very much.

 

[HutchinsonJC]

How much would downclocking by 100MHz help the power consumption in the context of keeping the 4 memory channels for what you want to do instead of turning off cores outright?

 

[StefanR5R]

If the application is bottle-necked by RAM (and can't be optimized to fit into the caches), then it may not even be able to drive the processor to its power limit.

 

[moinmoin]

Because I don't want to deal with 280W on air since I don't do liquid.

You don't have to deal with it at all, the CPU will handle it for you, at stock automatically. Just stick a sufficient air cooler on it and stop worrying about every little detail.

 

[Topweasel]

You don't have to deal with it at all, the CPU will handle it for you, at stock automatically. Just stick a sufficient air cooler on it and stop worrying about every little detail.

That's a good point. Kind of how like the 9900k works. Stick a heatsink on it. If its not enough to cool the thing it will down clock the CPU. Just get the big honking Noctua and call it a day. Maybe get faster RPM fans.

 

[StefanR5R]

and stop worrying about every little detail.

He will, once it becomes clear how difficult it will be to buy one anytime soon.

 

[extide]

Because I don't want to deal with 280W on air since I don't do liquid.
But maybe this PTT setting will do the trick.

Then just turn the power down in Ryzen master. Or let it run stock with whatever cooling you have, it will throttle so it won't burn up and give you the best performance you can get with your existing cooling. Just let it do it job, no need to mess with it.

 

[uzzi38]

How much would downclocking by 100MHz help the power consumption in the context of keeping the 4 memory channels for what you want to do instead of turning off cores outright?

It's always easier to just PPT with Zen based products. Drop PPT until the cooler can do the trick without an issue and carry on all happy.

Course, this is assuming you have an issue with temps in the first place. If you don't, then why bother?

 

[Markfw]

That's a good point. Kind of how like the 9900k works. Stick a heatsink on it. If its not enough to cool the thing it will down clock the CPU. Just get the big honking Noctua and call it a day. Maybe get faster RPM fans.

I have a Noctura, the big TR4 one on my 2970wx, thats 24 cores. The new 3960x should be no more than mine for power and cooling, and it does just fine.

 

[Kedas]

Course, this is assuming you have an issue with temps in the first place. If you don't, then why bother?

You also have noise and case temp that you want to keep under a certain level. There are more than one requirement that have to fit.
Certainly if it also has an 250W GPU inside.

 

[Magic Carpet]

If you are worried, that much about heat inside your case/room, then liquid cooling is the only way to go, since you can move it anywhere you need (e.g. basement), but it won’t be cheap.

 

[Soulkeeper]

My experience with disabling cores either in the bios or OS is that power usage stays about the same.
These chips are so good at instantly powering up/down in microseconds and powergating that it makes no real difference.
So a cpu with a few cores disabled will idle essentially at the exact same as not having them disabled. Full load might be a little lower, but not much.

 

[Kedas]

Yeah, I think PTT is the option, not disabling cores, more cores at lower clock should give faster results than less cores at a higher clock anyway in the same TDP for parallel workload. And then it wont feel like wasted money

This graph is interesting, nice power drop with limited performance hit.

https://pbs.twimg.com/media/D_mJ2PAU4AEJ4Ii?format=png&name=orig

That looks the same (or better) than what they promise for 'eco-mode'
So I guess eco-mode is an easy way of setting PTT lower

 

[Shmee]

I wonder how good these will be for gaming? I don't need 24 Cores, but if they can clock to the moon...also 4 channel memory is nice.

 

[JoeRambo]

I wonder how good these will be for gaming? I don't need 24 Cores, but if they can clock to the moon...also 4 channel memory is nice.

Yeah, 4 channels are nice. I think with AMD one already pays latency price with IO + chiplet design, so there won't be much extra latency penalty going from 2 to 4 channels. While at same time, L3 resources to mitigate latency increase with more chiplets.
We will see in several hours, but maybe AMD put some extra resources in IO chip for TR, something that is not found on dual channel IO chips, but useful on server grade chips where there are numerous chiplets.