When should I invest in a low TCP CPU?

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vegeta

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Aug 22, 2017
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I read a lot, the CPU uses his max TCP only when stressed.

So does that mean L-cpu's are often super-power CPU's that can do the same work with less power?

I was planning on getting the PassMark - Intel Xeon E3-1265L @ 2.40GHz - Price performance comparison, as the v2 is double the price for +20% performance. Lots of Gen8 MicroServer users als like this CPU PassMark - Intel Xeon E3-1220L V2 @ 2.30GHz - Price performance comparison with only 17 watt.

In my scenario:
  • I want to have a remote back-up server, back-ups happen nightly and take around an hour or 2 max.
I have even read some guy saying that it wouldn't matter, because the low-TCP would take 40 seconds for a job that a high-TCP CPU would do in 20 seconds. But that would mean I cannot trust Passmark anymore as some low TDP CPU's are very powerful.

Who should be looking for low-TCP CPU's? Server users with heavy load, homelab users with heavy load, or homelab users who want an extra remote server who's there for the back-ups
 

Marsh

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May 12, 2013
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I want to have a remote back-up server, back-ups happen nightly and take around an hour or 2 max.
2 hours usage per night, there is no benefit or payback for power saving.
You may need to wait 5-10 years for the payback.
Find the cheapest CPU , call it done.

BTW, just received a $40 E3-1220 v2 cpu from ebay seller.
 

wildpig1234

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Cheapest cpu for the best speed that fast enough.. you dont buy 1 low tdp cpu to save energy money.... you need to buy a whole lab worth to make any difference
 

wildpig1234

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Cheapest cpu for the best speed that fast enough.. you dont buy 1 low tdp cpu to save energy money.... you need to buy a whole lab worth to make any difference
 

vegeta

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Aug 22, 2017
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Maybe you are right, but you guys are from the United States. I understand that for you the energy prices are halve or less, but here there are quiet high.

I completely understand that everybody takes dual R610 servers with 64 or even 128 GB Ram for only $350 if power costs are reasonable.
PassMark - [Dual CPU] Intel Xeon X5482 @ 3.20GHz - Price performance comparison
Passmark score is great too.

But I'm from Europe and I'd be great to have an indication how much a server would cost me over 3 years. Average energy expenditure per family here is €1.800 yearly.


Calculator: Verbruiken.nl

I'm just trying to have an understanding of power consumption in computers in general, but I don't get farther than a few statements, even while watching Linus's tech videos.
 

Marsh

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Power saving is delta of power usage between processors A and processor B
Example: Processor A use 25w , processor use 30w. The rest of the system is the same
The difference is 5w , 2 hours per day is 10w , 100 days is 1KWH saving . 400 days is 4KWH saving.

We are in Calif, higher usage power rate is $0.4 per KWH , 400 days power saving is $1.60.
 

i386

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Mar 18, 2016
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Usually low tdp cpus are used in applications where cooling is limited, think of industrial pcs and similar.

But I'm from Europe and I'd be great to have an indication how much a server would cost me over 3 years.
That's hard to answer and looking at the cpu tdp alone is not enough. You can have a 25 watt cpu in a storage server and the fans + hdds/ssds would consume most of the power. (157watt total power consumption with 10 6tb hdds, 2 200gb sssds, 1 raid controller and 5 supermicro fans. The cpu consumes less than 20% of the power)
 
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Marsh

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Rand__

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I think the point here (as stated before) is that the difference in consumption between 2 possible CPUs you are looking at would need to be quite high to offset a higher buying price.

Yes of course it makes sense to get the most energy efficient cpu (which is key here, not low TDP) but not at any price. What you need is CPU power per Watt, that over several generations and product lines compared to current buying prices (including ebay o/c) :)
This would enable you to get what you are looking for.

As long as you don't find it, do the next best thing and look at it in a more abstract way.
1. CPU is only a part of the system. Disks, Fans, Drives, PSUs and Memory take power too. More modern components take less power
2. CPU usually is not the bottleneck on backup operations unless you're going to spec out a larger system - any Celeron can hit 100 MB/s transfer speed over a 1 GB net. Encryption & compression are different topics, but you have not specified those.

Also I think you need to define a couple of other criteria - is that box powered 24/7 or only during backups (2h)? What is your network connectivity, backup target (disk, tape), performance target (1 GB, 10GB, as fast as possible, as efficient as possible), what about the backup (client) data ( are those boxes on anyway, are they shutdown after backup), as mentioned do you want/need encryption, compression, deduplication, what target OS are you looking at, Raid or not ...
 
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Chris Web

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The newer xeons have very good power saving technology so idle power consumption is probably on par with low tdp parts.

Sent from my HTC 10 using Tapatalk
 

Chris Web

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The newer xeons have very good power saving technology so idle power consumption is probably on par with low tdp parts.

Sent from my HTC 10 using Tapatalk
If you are using it under load 24/7 then you will see some power savings, but if it's idle most of the time, I'd go with the newest xeons you can afford

Sent from my HTC 10 using Tapatalk
 

msg7086

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TDP itself is all about cooling requirement.

Sometimes lower TDP parts can cost you more on power bill under certain situation.

Let's assume 2 CPUs are running at the same performance per watt. In this case, a 100w CPU can run CPU intensive tasks in half of the time compared to a 50w CPU. The total power consumption will be almost the same. Or, it can run twice amount of tasks -- and produce more profit for you, if you can make money out of it and forget about the power bill.
 

wildpig1234

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Aug 22, 2016
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like others had said. lower tdp is really more about having to constraint yourself to meet a lower cooling requirement and smaller cases, etc and having to restrict yourself to lower performance level for the strict need to meet the lower cooling requirement....

The benefit of saving energy is minimal and only very limited at best.

you don't "save" on energy by buying lower tdp part, you save energy by buying newer more efficient architecture or manufacturing fabrication.
 

Rand__

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actually you can save a little bit of energy by picking the most efficient CPU in a line. Eg in e5v4 it was the 2640 (iirc). But that might or might not be a low TDP part and is not related to it