[SOLVED] What is the average CPU Power effeciency ?

[Mezoxin]

For example if my cpu consumes 180w , how much watts are lost as heat ? I am just trying to make sense of cpu coolers TDP ratings , and how CPU power consumption translates to coolers TDP ratings

because I see after market coolers being rated at things like 250 TDP where in fact even the most power hungry cpu's almost actually consume that much power
another example my CPU under Extreme prime 95 strress scenarios reach power consumption of around 180w , which make my Coole Hyper 212 unable to cool it under 100c ,although the cooler is rated at 140TDP , which means that my cpu power effeciency is probably lower than 22%

 

[13thmonkey]

I'm not sure you understand efficiency, how do you reach 22%? it's got nothing to do with comparing 180W and 140W.
You can only really understand relative efficiency, i.e. how much power does it take for a processor to do a set of calcs, vs another process on the same calcs.

 

[jojesa]

You are confusing TDP with power

For example if my cpu consumes 180w , how much watts are lost as heat ? I am just trying to make sense of cpu coolers TDP ratings , and how CPU power consumption translates to coolers TDP ratings

because I see after market coolers being rated at things like 250 TDP where in fact even the most power hungry cpu's almost actually consume that much power
another example my CPU under Extreme prime 95 strress scenarios reach power consumption of around 180w , which make my Coole Hyper 212 unable to cool it under 100c ,although the cooler is rated at 140TDP , which means that my cpu power effeciency is probably lower than 22%

I think you are mixing up TDP (Thermal Design Power ) with power usage (Watts).
TDP is not a measure of power power consumption....even though TDP is correlated with power consumption. The more power CPU uses the higher the TDP.
TDP is used as a guide line and I don't think manufacturers take in consideration torture test like prime95.

 

[Mezoxin]

I am trying to correlate the cpu power consumption to how much of that power is dissipated as heat , and thus giving us that TDP rating that cpu manufacterers and Coolers put on their product
In order to be being able to utilise the tdp rating that manufacterers put on their cpu coolers (since intel ratings arenot that practical) , with my real time usage needs

 

[13thmonkey]

The TDP for a processor is simply how much heat energy a processor generates per second, the TDP for a cooler is how much heat energy it can get rid of in a second (based on some generally undefined level of airflow and ambient temperature). Dividing one by the other gives a clue as to how under or oversized the cooler is, but the definitions for the cooler are so weak and similarly for the CPU that it's kind of pointless unless you aim for a factor of 1.5-2 oversized.
Comparing the electrical and thermal energies doesn't tell you much either.
Take a FX8350, probably 100W of electrical and thermal power output.
Take an i5-3570k, probably 65W of electrical and maybe 90w of thermal power
The i5 could do the same amount of work faster than the FX for less electrical power and less thermal power. It is therefore more efficient, but you can't put a number on it easily. Like 65W gets you a cinebench score of 3000 and 100w gets you a score of 2500 (made up numbers) you can then start to calculate something that looks like efficiency, as the 3000 and 2500 are score for a set amount of computation factored by how long it took.
Comparing Electrical to thermal power ratings just tells electrically how efficient it is great if you are looking at a heater, but it could bare no relationship to it's computational effectiveness, it's more likely to tell you how they measure TDP.

 

[13thmonkey]

If you are just trying to match heat load to cooler TDP then just 'go big' you can't overcool a CPU, and the TDP of the cooler will depend on the ambient temp. A 140W tdp might be at 20C ambient, if your ambient becomes 30C on a hot day then that would be reduced as it is all based on the temperature difference between the source and the sink, i.e. processor and the air.

 

[InvalidError]

For example if my cpu consumes 180w , how much watts are lost as heat ?

CPUs are approximately 100% efficient at converting power to heat - practically every watt going under the IHS will ultimately come out as heat, though a small part of it will be dissipated by the PCB, traces and whatever is connected at the end of IO lanes.

 

[Mezoxin]

CPUs are approximately 100% efficient at converting power to heat - practically every watt going under the IHS will ultimately come out as heat, though a small part of it will be dissipated by the PCB, traces and whatever is connected at the end of IO lanes.

You are correct thats why intel doesnt diffrentiate the values of TDP from PL1

https://www.anandtech.com/show/1354...5550.826833457.1572723115-64356977.1572466937

 

[Mezoxin]

Can Someone explain though why my CPU is reaching 180w of power consumption although according from what i understand the maximum value i should reach is the PL2 , and according to intel spec sheet
intel.com/content/dam/www/public/us/en/documents/datasheets/8th-gen-core-family-datasheet-vol-1.pdf

PL2 = 1.25 x PL1(which is equal to TDP)
So it should be 119 w and not north of 180w
119= 1.25 x 95

 

[13thmonkey]

how do you know 180W?

 

[Mezoxin]

how do you know 180W?

this under Prime 95 , readings on HWmonitor and from my PSU Corsair Link

[SOLVED] - Why is a stock i7 9700k reaching 180 watts during prime

When i run prime 95 everything is running normal for up to approximately 5mins as seen here , with system total consumption at 176w as seen in the corsair link and cpu at 114 as seen on hwmonitor all of the sudden the wattage starts ramping up to 252w system and 184 cpu and ofcourse...

forums.tomshardware.com

 

[13thmonkey]

No idea, but this why I oversize my coolers.

 

[Mezoxin]

No idea, but this why I oversize my coolers.

Thermals aside , I just want to make sure that this is a safe wattage to operate my processor at
I will be getting a be quiet dark pro 4 by the end of the week though , just not that excited about overclocking since I am already exceeding Intel‘s spec for wattage when at stock

 

[TJ Hooker]

Can Someone explain though why my CPU is reaching 180w of power consumption although according from what i understand the maximum value i should reach is the PL2 , and according to intel spec sheet
intel.com/content/dam/www/public/us/en/documents/datasheets/8th-gen-core-family-datasheet-vol-1.pdf

PL2 = 1.25 x PL1(which is equal to TDP)
So it should be 119 w and not north of 180w
119= 1.25 x 95

You can set PL2 in the BIOS. Motherboard manufacturers can and do increase the default value of PL2 to improve CPU performance with their boards.

 

[Mezoxin]

You can set PL2 in the BIOS. Motherboard manufacturers can and do increase the default value of PL2 to improve CPU performance with their boards.

if I stick to intels specification specially for the pl2 duration as well “Tau” that is going to significantly decrease my performance , I just want to understand the reasoning by how is this high deviation from Intel specs is done and tolerated by almost all motherboard manufacturers , and is it safe ?

 

[atljsf]

intel has been adapting tdp and power consumptions for years to fit their statements, but what you get and what you were told you would get is different

if you connect the whole pc to a killawatt and you know how much the gpu you have use you will see that numbers are very different than what you were told a intel cpu consumes

just take a look at the recent threadripper in gamers nexus channel on youtube, those numbers in terms of power consumption are telling alot of things

they don't measure power consumption with a killawat, they use a clam that measures the amps on the eatx 8 pin power connectors

afik, any electricity passing trough a transistor or a resistance will convert in part into heat, the entire 180 watts are not converted into heat, but a good part is

i don't remember where i read that if transistors and resistors were abit more efficient we shouldn't generate half of the heat these units generate, but with current technology tht is what we get, decent efficiency and lots of heat wasting electricity in the process

 

[jojesa]

Can Someone explain though why my CPU is reaching 180w of power consumption although according from what i understand the maximum value i should reach is the PL2 , and according to intel spec sheet
intel.com/content/dam/www/public/us/en/documents/datasheets/8th-gen-core-family-datasheet-vol-1.pdf

PL2 = 1.25 x PL1(which is equal to TDP)
So it should be 119 w and not north of 180w
119= 1.25 x 95

A 9700k could reach above 200W depending of frequency and workload.
95W is calculated when operating at base frequency (3.6GHz) "under an Intel-defined, high-complexity workload "

 

[TJ Hooker]

if I stick to intels specification specially for the pl2 duration as well “Tau” that is going to significantly decrease my performance , I just want to understand the reasoning by how is this high deviation from Intel specs is done and tolerated by almost all motherboard manufacturers , and is it safe ?

It's done because it improves performance. If you review two mobos and one abides by Intel's specs and the other doesn't, the latter will have noticeably better results. So mobo manufacturers are incentivized to raise the limits to whatever they think the board itself can handle. It also allows higher end boards to leverage their more robust VRMs even if the end user isn't going to OC.

Intel washes their hands of the matter by saying they leave it up to the mobo manufacturers to set tau/PL2 as they deem appropriate (CPU datasheet be damned). It benefits Intel too because it makes their CPU performance look extra good.

As long as you're keeping the CPU cool it should be safe. P95 is going to be more power hungry than just about any real workload anyway, especially if you have AVX enabled.