Can't get below 40W idle on Haswell CPU.

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jormartr
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Can't get below 40W idle on Haswell CPU.

Post by jormartr » Thu Feb 26, 2015 1:29 pm

Hello,

I have a new computer with an i7-4790, 3 SSD disks and 32GiB of memory.

For some days since I started using it I was measuring ~20W at idle load with it, since I touched something on BIOS I can not get it to go below ~40W.

I have tried to reset the BIOS and load default values but doesn't help. I don't get what can be the cause, I don't find anything obvious on BIOS settings, everything seems correct.

Any hint about this?

CA_Steve
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Re: Can't get below 40W idle on Haswell CPU.

Post by CA_Steve » Thu Feb 26, 2015 2:53 pm

Tracked down your build thread so we have an idea of what's in it. :D

Run CPU-Z and the task mgr (cntl-alt-del) to see if the cpu is idling and what tasks are running. Maybe something is loading at start up that shouldn't be or isn't idling out.
1080p Gaming build: i5-4670K, Mugen 4, Asrock Z97 Anniversary, MSI GTX 1660 Gaming X, 8GB 1866 RAM, Samsung 860 Evo 500GB, Crucial MX100 256GB, WD Red 2TB, Samsung DVD burner, Fractal Define R4, Antec True Quiet 140 (2 front + rear) case fans, Seasonic SSR-550FX. 35W idle, 45-55W video streaming, 170-200W WoW, 318W stress test (Prime95 + Furmark)

Lucky Luciano
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Re: Can't get below 40W idle on Haswell CPU.

Post by Lucky Luciano » Thu Feb 26, 2015 3:30 pm

Make sure the settings mentioned in the link below are explicitly set as On or Enabled instead of Auto
http://www.xbitlabs.com/articles/cpu/di ... ing_2.html
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mobo ASRock Z97M Pro4 | cpu Intel Pentium G3258 @ 4.2 GHz | cooler Scythe Kotetsu | ssd Intel 530 | hdd Seagate NAS

Abula
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Re: Can't get below 40W idle on Haswell CPU.

Post by Abula » Thu Feb 26, 2015 3:41 pm

Use balanced as your power settings under windows, if you dont allow it down clock to 800mhz it will never go down to 20W idle.
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jormartr
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Re: Can't get below 40W idle on Haswell CPU.

Post by jormartr » Fri Feb 27, 2015 12:17 pm

Hi guys,

thank you for your answers!

I've checked all settings on BIOS. As I use Linux I've not been able to use Windows tools, but anyway I managed to stop any program so I got the cpu at 800Mhz almost 100% of the time, and it went down to 34W.

I start to think that my wattage measure gadget is not working correctly, it did some strange thing before, so I realize that my real power consumption is on 40W on idle desktop usage.

Tzeb
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Re: Can't get below 40W idle on Haswell CPU.

Post by Tzeb » Fri Feb 27, 2015 2:14 pm

Either the gadget is broken or something is wrong with the mobo or pico. That build, even with a few 12CM low rpm fans and an efficient psu, should not pull more than 25W at idle.

jormartr
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Re: Can't get below 40W idle on Haswell CPU.

Post by jormartr » Fri Feb 27, 2015 2:48 pm

Tzeb wrote:Either the gadget is broken or something is wrong with the mobo or pico. That build, even with a few 12CM low rpm fans and an efficient psu, should not pull more than 25W at idle.
Thank you very much for the suggestion, didn't think about that. But I changed the power supply and the consumption was the same.

I think I got confused by this kill-a-wat like which is broken.

Tzeb
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Re: Can't get below 40W idle on Haswell CPU.

Post by Tzeb » Fri Feb 27, 2015 2:54 pm

Get another kill-a-wat, or an ups with usb and let us know the real idle pull.

jormartr
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Re: Can't get below 40W idle on Haswell CPU.

Post by jormartr » Thu Mar 05, 2015 1:14 pm

Hi guys,

got another measure gadget, same results.

I guess 37W is my absolute minium (with 3 ssd), not that bad compared to my old Q6600.

Thank you again!

Tzeb
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Re: Can't get below 40W idle on Haswell CPU.

Post by Tzeb » Thu Mar 05, 2015 2:38 pm

Something is wrong on your part.

I've tested another build yesterday.

g3258
GA-H81M-DS2
4GB DDR3 @1.5V
1 ssd
2 12 CM fans@~550 RPM
Some crappy FSP ATX-400PNF (don't think efficiency is strong in this one :lol: )

Idle is at ~21W, sometimes ever under 19.

37W idle is bad. You should see half that with a good psu.

Vicotnik
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Re: Can't get below 40W idle on Haswell CPU.

Post by Vicotnik » Fri Mar 06, 2015 2:52 am

The motherboard is usually what makes up at least some of the difference. I would guess that the GA-H81M-DS2 is more efficient at idle compared to the GA-Q87M-D2H.
Main: ASRock B85M-ITX | i3-4330 | 16GB DDR3 | Intel 730 240GB | HDPLEX H1-S | picoPSU | No moving parts | Idle 13.9W
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Gaming: Intel DH77EB | i5-3570K | GTX 1060 6GB | 16GB DDR3 | TJ08-E | RM750X
Server: ASRock N3150-ITX | ~30TB | G-360 | Idle ~25W

Tzeb
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Re: Can't get below 40W idle on Haswell CPU.

Post by Tzeb » Fri Mar 06, 2015 6:18 am

That q87m can't make THAT much of a W difference if all is working as it should. At first he was reading ~20W.

Here is what i would do...

Leave just one stick of ram, just the boot ssd drive, disconnect any fans or whatever could pe removed. Boot, wait for idle, measure.

If you don't read under 25W, something is broken for sure.

jormartr
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Re: Can't get below 40W idle on Haswell CPU.

Post by jormartr » Mon Mar 09, 2015 3:41 pm

There is not much I can remove. Only the front 18cm fan and three of the four memory sticks.

Based on what you say something must be wrong. I suspect it is related to the motherboard, but resetting BIOS didn't make any difference neither, I have to recheck that and the hardware.

alecmg
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Re: Can't get below 40W idle on Haswell CPU.

Post by alecmg » Tue Mar 24, 2015 4:37 am

jormartr wrote:Based on what you say something must be wrong. I suspect it is related to the motherboard, but resetting BIOS didn't make any difference neither, I have to recheck that and the hardware.
From my linux days I remember having a bit similar trouble. CPU in idle would drop clocks but not volts. Wrong kernel or wrong speedstep module, I dont remember.
It could explain 15-20W difference on a normal CPU, but a low power T version? Not sure.
[size=75]#6) Plug in one device at a time, stick your fingers in your ears, close your eyes, and hit the power switch with a toe[/size]

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