Why is my CPU not running at max published speed?

In summary, the conversation discusses the issue of a machine with a published max speed of 5.0 GHz only reaching up to 4.5 GHz when running under load on all 4 cores. The cause of this limitation is explained to be due to modern CPUs being limited by power dissipation and throttled to prevent overheating. It is also suggested that the performance issue may be mostly software-related and not necessarily due to the clock speed. Possible solutions, such as using parallel processing options or liquid cooling, are mentioned. Furthermore, it is stated that the purchased RAM may also contribute to the bottleneck. The conversation ends with the conclusion that the chip will run one core at 4.9 MHz and four cores at 4.0 MHz
  • #1
aheight
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TL;DR Summary
How can I get my CPU to run at max turbo-boost speed?
I have a Intel(R) Xeon(R) E-2274G CPU @ 4.00GHz 4.01 GHz machine which has a published max speed of 5.0 GHz. However, when I run it under load on all 4 cores, it only gets up to about 4.5 GHz: Could someone explain to me why it's not ramping up to the full 5.0 GHz or what I could do to increase the speed without overclocking it? I have a practical reason for this: I wait a long time for my work to complete so would cut down the wait time if I could do something to increase the speed.

Thanks,

cpuload.jpg
 
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  • #2
aheight said:
E-2274G CPU @ 4.00GHz

See the 4.00 GHz? Why do you expect 5 GHz?
 
  • #3
Modern CPUs are limited by power dissipation. The speed is throttled so they don't overheat. It may well be running at 5GHZ for short periods of time. The 4.52 GHZ you are seeing is probably an average speed.
 
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  • #4
Vanadium 50 said:
See the 4.00 GHz? Why do you expect 5 GHz?

Slight error. I meant 4.9 GHz: When I purchased it from hp.com, the quoted specs were:

Intel® Xeon® E-2274G Processor (4.0GHz, up to 4.9GHz w/Boost, 8MB cache, 4 core) + Intel® UHD Graphics P630

just wondering why I can't get it up to this speed. I'm running Mathematica "ParallelTable" which is using all cores. Does the 4.9 figure apply when only one core is running or is the speed being reduced because of heat flow. If so under what conditions can I see the speed at the full published figure of 4.9 for an extended period rather then just a spike I was wondering?
 
  • #5
phyzguy said:
Modern CPUs are limited by power dissipation. The speed is throttled so they don't overheat. It may well be running at 5GHZ for short periods of time. The 4.52 GHZ you are seeing is probably an average speed.

Ok, sorry, didn't see this before I posted above. Basically then it's just a heat problem? Little misleading to say 4.9 when, as I watch the task manager it never gets this high or may just spike to this. Disappointing I guess. Purchased it to reduce wait time, ramped up the CPU load a bit and here I am waiting just as long as before I got it.
 
  • #6
I do not know what you are doing, so I am assuming lots of floating point operations.

Unless you have profiling in place and are seeing a cause, asserting that clock speed is the primary driver of completion time -- may not fly.

Generally about 80% of performance issues are software (your program) related. For example, data locality issues with large arrays, or failure to use parallel processing options. After installing CUDA and NVDIA GeForce 960, then parallelizing I got a 70% speedup. Mostly on loops. Your options are not necessarily going to be anything I just mentioned.

Ulrich Drepper, when not playing curmudgeon, has a lot of good things to say. Yes, this is dated but all of the concepts are very insightful, IMO. And it shows that you need to understand your archectecture to make good decisions.

http://www.sgidepot.co.uk/misc/cpumemory.pdf
 
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  • #7
I have an Asus gaming laptop. When I put it in turbo mode, it also speeds up the fans so much that the fan background noise becomes a fan roar. It also monitors the temperatures and silently turns down the clock speed to limit max temperature.

I understand that other gaming systems have liquid cooling.

It's not trivial to just speed up the clock.
 
  • #8
anorlunda said:
It's not trivial to just speed up the clock.
 

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  • #9
Maybe the RAM I purchased is the bottle-neck. I got 32 GB of DDR4 2666 NECC RAM which is believe is buffered. I think the 2666 means it's operates at 2.666 GHz? I just ran something that took 1 hour to finish at 4.5 GHz. Would unbuffered RAM have made a significant difference?
 
  • #10
Did you look up the chip on Intel's?

Intel® Turbo Boost Technology 2.0 Frequency is the maximum single core frequency at which the processor is capable of operating using Intel® Turbo Boost Technology.

You are using 4 cores and keeping 2+ busy.
 
  • #11
On that Task Manager view right click and select "Change graph to > Logical processors." What is almost certainly happening is that you have 4 or more CPU's and your program is only designed to use one of them. If that is so you will see one CPU maxed while the others are not. That is a software programming issue, the software has to be programmed to use all the available cores.
 
  • #12
Here is a screen shot of my Mathematica session. I'm basically running a 2000 length table of Newton Iterations to find roots of very high degree polynomials of high precision using Mathematica's built-in parallel-processer "ParallelTable". This launches 4 kernels. As the iterations of each table index is completely independent of the others, I can run them in parallel (4 at a time). As you can see at the left, Mathematica is using four kernels (cores) as each kernel is reporting the table index mod 25 and the Task Manager Resource Monitor showing 8 logical cores running at 111% of maximum I think. I don't understand if HP states the CPUs can reach 4.9, why the max I see on the usage is 4.5? I'm just saying that's 4 MHz difference which is significant I think.

cpuStats.jpg
 
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  • #13
aheight said:
I don't understand if HP states the CPUs can reach 4.9

Read what Intel says. One core.

Your chip will run one core at 4.9 MHz and run four cores at 4.0 MHz. You're getting 4.5 MHz. That's 12% better than promised. You should be happy.
 
  • #14
Vanadium 50 said:
Read what Intel says. One core.

Your chip will run one core at 4.9 MHz and run four cores at 4.0 MHz. You're getting 4.5 MHz. That's 12% better than promised. You should be happy.

Ok sorry. Didn't quite understand what you said above. 4.5 is still pretty fast.
 
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  • #15
The performance of a computer is limited by a number of factors

a) the CPU speed
b) the I/O speed - how fast can you read/write from/to disk
c) the memory bandwidth - how fast can you read/write from/to memory
d) the quantity of memory - whether you are paging the memory in and out.

The CPU is often waiting for data to be retrieved from disk or memory, for data to be written to disk or memory. It is why modern CPUs have 2 virtual CPUs per core - while one CPU is stalled waiting the other can process its data.

It is very rare for even a well optimised program to run at 100% CPU (except for a trivial program needing no data from memory and doing no I/O).

See the Top 500 supercomputers list where supercomputers typically run at about 70% CPU (Rmax / Rpeak) even with highly optimised Linpack test cases.

An analysis of what is causing the CPU to run slowly identifies what needs upgrading: faster I/O, faster memory, more memory.
 
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  • #16
I once had to figure out how long a specific problem using a finite element code was going to run on an exoscale sytem. According to the code developers, less than 10% of the time to run was floating point operations.
 

Related to Why is my CPU not running at max published speed?

1. Why is my CPU not running at its max published speed?

There could be several reasons for this. One possibility is that your CPU is being limited by the cooling system. If the temperature of your CPU exceeds a certain threshold, it will automatically reduce its speed to prevent damage. Another reason could be that the power supply is not providing enough power to support the maximum speed of the CPU. Additionally, there may be software or BIOS settings that are limiting the CPU's speed.

2. Can I manually increase my CPU's speed to its maximum?

In some cases, it is possible to manually overclock your CPU to run at its maximum speed. However, this can be risky and may void your warranty. It also requires knowledge and experience with hardware and software settings. It is recommended to consult with a professional before attempting to overclock your CPU.

3. Is it normal for my CPU to not run at its maximum speed all the time?

Yes, it is normal for your CPU to not run at its maximum speed constantly. Most CPUs have a base clock speed and a boost clock speed. The boost clock speed is only activated when the CPU is under heavy load. The CPU will adjust its speed based on the demands of the tasks it is performing in order to conserve energy and prevent overheating.

4. Will not running at its maximum speed affect the performance of my CPU?

Not necessarily. While running at its maximum speed can provide a performance boost, it is not the only factor that affects overall performance. The type and number of cores, cache size, and other hardware components also play a significant role. Additionally, the speed at which your CPU runs is also dependent on the software and tasks being performed.

5. Should I be concerned if my CPU is not running at its max speed?

If your CPU is not running at its maximum speed, it does not necessarily indicate a problem. As mentioned before, it is normal for CPUs to adjust their speeds based on the demands of the tasks they are performing. However, if you notice significant performance issues or your CPU is consistently running at a lower speed than expected, it may be worth investigating potential causes or seeking professional help.

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