Underclocking haswell to lower max TDP

[Axn40]

Hi everyone,

I have read a few topics on the above mentionned problematic but haven't found a solution.

I have a 65W Core i5 4570s mounted on a mini ITX Asus Z97i-Plus.
I would like to switch to a fanless Akasa case which can cope with up to 35W TDP cpus : http://www.akasa.com.tw/search.php?seed=A-ITX19-A1B

My motherboard is among the 4 which are compatible with the case...

Instead of buying the newer Core i5 4590T I'd like to underclock and undervolt mine to 2GHz base clock and eventually 3GHz Turbo.

I have looked at voltage offset, and various Intel XTU options, but multipliers are grayed out (even to lower them down)

The idea would be that the processor never exceeds 35W.

Is it feasible? If yes what would be the best way to do it?

 

[ShintaiDK]

You may have the option simply to set a 35W power target in BIOS.

 

[Axn40]

I have not found any "target" TDP setting in Z97i-plus BIOS.

 

[LTC8K6]

Try the Windows power settings? The advanced settings should let you set the max processor power to something like 45%.

 

[coercitiv]

Try the Windows power settings? The advanced settings should let you set the max processor power to something like 45%.

That might limit performance more than necessary (especially ST).

If TDP cannot be configured via BIOS, best alternative is setting lower base/turbo speeds for the CPU (different values for 1/2/3/4 core loads) and maybe using CPU Power Thermal Control to enforce some kind of throttling when needed. (don't know what values this allows, lower values might help keep the entire system "chilly"). Downside is it requires a bit of testing to figure out which values to set for max clocks.

Another simple approach is to install Intel XTU and configure TDP via software. Downside is potentially lower reliability since it's a software solution. (any BSOD triggers a protection feature that resets settings)

 

[LTC8K6]

Well, he mentioned that XTU doesn't work, so I think that is out.

 

[LTC8K6]

I don't see where it says that the case is limited to a 35W cpu?

 

[BSim500]

The idea would be that the processor never exceeds 35W. Is it feasible? If yes what would be the best way to do it?

You can guarantee it won't ever go over 35w by lowering:-

Control Panel -> Power Options -> Balanced -> Change Plan Settings -> Change Advanced Power Settings -> Processor Power Management -> Maximum Processor State.

If it's any use, testing on my "77w" i5-3570 the "percentage steps" combined with a mild -0.1v undervolt are as follows:-

5% = 1.6GHz @ 0.680v (approx 20w)
65% = 2.2GHz @ 0.728v
80% = 2.6GHz @ 0.768v
90% = 3.0GHz @ 0.832v (approx 35w)
100% = 3.4GHz @ 0.888v (approx 48w)
100% + mild OC = 3.8GHz @ 0.976v (approx 54w)
100% + mild OC = 4.0GHz @ 1.005v (approx 59w)

NB: Above are all load voltages under Prime95 not idle. Obviously the "silicone lottery" determines default VID table and "how low you can go" which varies from one chip to another. You may get different figures for Haswell vs Ivy Bridge too.

The bigger question is what will you be using it for? If you're using it as just a basic netbox / workbox which rarely loads 100% and "spikes" up for just very short periods (eg, less than 2 seconds whilst loading a web page / opening a Word doc then idles 99% of the time), you could possibly get away with undervolting your i5-4570S without underclocking it (probable 35-45w range). OTOH, even a 35w CPU in a 35w thin enclosed fanless case can get a little hot if 100% loaded doing say x264 encoding for hours on end, and it isn't just the CPU that heats up under such conditions, but also motherboard components & particularly any mechanical HDD's, as there's literally no airflow. I've seen some HDD's (which normally run 25-30c in a decent actively cooled case) build up to 60-65c in thin enclosed fanless boxes when people try and use them as "miniature workstations" as sealed "fansink" cases don't always draw heat away from secondary components the same way they do the CPU.

So it really boils down to your usage scenario. If you haven't ordered that Akasa and plan to do constant heavy load stuff, personally I'd look for a slightly larger Mini-ITX case with a silent fan simply to keep all components cool. If you only do light stuff, eg, Word, web browsing, you can probably get away with simply undervolting your i5-4570S chip maybe even without underclocking if you don't load it up 100%. I wouldn't bother swapping your CPU for a 2GHz "T" chip though just for that case as you can often get better perf pushing an undervolt to the stability limit (same way overclockers do) at a higher "S" class 2.5-3.0GHz clock with 65%-95% Speedstep tweaks and enjoy 30-50% higher perf at almost the same wattage.

 

[Axn40]

Hi everyone,

I have looked at voltage offset, and various Intel XTU options, but multipliers are grayed out (even to lower them down)

As mentionend, I have already looked into XTU, but can't find any TDP or Temp related target, and turbo clocks are grayed...

I had seen that message about power management, but I'll automatically lose the turbo if I use it.
Moreover, setting it at 70% effectively brings the max frequency to 2GHz and apparently limits the heat (monitored in XTU) to 55~58°c under stress test, but wouldn't be enforced until windows is launched...
By the way, how did you calculate or measure your TDP estimates

The ideal would be to implement a undervolting/underclocking directly in the bios, but:
- How to benchmark under win7 in order to find the right frequency / voltage to reach the most efficent 35W TDP balance
- Which voltage and intensity to "step down"?

 

[Axn40]

I don't see where it says that the case is limited to a 35W cpu?

It doesn't mention it on this page, but there: http://www.fanlesstech.com/2015/03/akasa-euler-m-overview.html

 

[sm625]

Moreover, setting it at 70% effectively brings the max frequency to 2GHz and apparently limits the heat (monitored in XTU) to 55~58°c under stress test, but wouldn't be enforced until windows is launched...

Why would that be a problem? The cpu shouldnt be loaded very heavily if windows isnt running. Also, the max frequency should be higher than 2GHz for single thread workloads.

 

[LTC8K6]

That says it will handle a 35W i7 "with ease". It doesn't set that as a limit.

Well, how often would the CPU be running under a heavy load?

I mean, the CPU may have a max TDP of 65W, but how often will it actually be anywhere near that number?

I would think the case will handle a 65W cpu okay, as long as it is not running a burn test.

 

[Axn40]

It is an issue because at POST the CPU is at full speed to start the OS.

It is 35W, I have red on a forum a guy trying it with a 45W xeon E3 and reporting overheating of the case, you also have it here https://www.caseking.de/akasa-euler-m-fanless-mini-itx-gehaeuse-schwarz-geak-053.html

Looking deeper in XTU there is the option to graph the Core TDP and the Package TDP.
Offsetting a bit the max current intensity (-3mA) in the BIOS, I reach 3.2 GHz (which should be turbo mode) for a reported Package TDP of roughly 20W but the temperature of the package reaches 72°c on a 2 min stress test...

Is that consistent? Taking into account the fact that it is cooled by the stock Intel fan, I don't quite see how a passive "case" could manage a 35 TDP if I already have those temps...

Am I doing something wrong?

 

[Dufus]

I have not found any "target" TDP setting in Z97i-plus BIOS.

You need turbo enabled which most likely means clamp option is not used which in turn means only turbo bins will be throttled with power limiting, base frequency can still run higher than PL1 / PL2.

Try ThrottleStop and hope Asus has not locked your registers.

If that doesn't work then try this.

35W.zip

 

[Yuriman]

You might find my thread useful:

http://forums.anandtech.com/showthread.php?t=2443083

Some food for thought: If we assume ~5w idle draw, under an AVX load and accounting for PSU efficiency @ ~80%, an Ivy Bridge desktop chip draws ~12w at 1600MHz, ~21w at 2600MHz, and ~36w at its maximum non-turbo frequency of 3400MHz. Going up another 600MHz increases power consumption by almost 50%, which makes it pretty clear why the stock frequency is what it is.

 

[unclewebb]

Adjusting the Maximum processor state in the Control Panel is a poor way to solve this problem because it reduces performance when the CPU is lightly loaded. The CPU will always run slow even when running a single threaded task and the power consumption is way under the 35 Watt target.

As Dufus mentioned, why not try ThrottleStop. If the bios has left the Package Power register unlocked then you can simply enter in 35 for the long term power limit. You could also enter 35 for the short term limit or maybe go slightly higher if your cooling can handle say 40 watts for a short period of time. One or two seconds or maybe half a second. You can adjust this to whatever you want.

If this register is locked then you can try using the PP0 register instead. This register controls the power consumption of just the cores. If you want total CPU power consumption to peak at around 35 watts then try using a number slightly less than 35 for PP0. Here is an example of ThrottleStop running the built in TS Benchmark.

http://i.imgur.com/9t6f7gN.png

A PP0 setting of 27 limits the CPU package power consumption to approximately 35 Watts. My 47 Watt 4700MQ is now a low power 35 Watt CPU and it didn't cost me anything to get this new feature. The CPU multiplier decreases just enough to keep power consumption in check.

Instead of an 8 thread load, when the CPU is only loading the equivalent of 4 threads, the CPU will automatically speed up.

http://i.imgur.com/VgPwYqV.png

It is still limited to 35 Watts though. The CPU will constantly adjust itself, making sure that it never exceeds your 35 Watt cooling solution no matter what type of software you are running. I wrote the program so I know the link Dufus posted is safe. If you think SendSpace is kind of shady then you can also download ThrottleStop from my Google Drive.

ThrottleStop 8.00
https://drive.google.com/open?id=0B0dpSo9k93jDTE1fcHNtbUMwdGc

 

[Axn40]

Thanks uncleweeb for confirming my opinion on the maximum processor power tweak.
I had already had a look at ThrottleStop (6.00), but didn't see anything realted to the package power register nor the long term power limit, I'll have a closer look at tutorials on how to use it
It doesn't solve my temps issue though, it can't be normal for a processor drawing 20w to reach 72°c in less than a minute, or is it?
I'll let you know how it goes
cheers

 

[Axn40]

Had a closer look to the "guide" and I actually realized you are most likely the same unclewebb as there:http://forum.notebookreview.com/threads/the-throttlestop-guide.531329/
I did a click on TPL and here is what I got:

So i guess that it is locked...
(BTW: I did click on limit reasons by curiosity, and the little yellow sqaures disapeared, should I worry about that?)

For the PP0 current limit the value is significantly higher than the one in your screenshot and not locked, is it normal?

I can set the PP0 Power limit to 27 and tick the clamp, if I understand well, only this should limit my core TDP to 27W==> total TDP ~35W right?

Thank in any case, I am progressing

 

[unclewebb]

In your screenshot, the Package Power Limits Lock box is not checked. That means that these power limits were not locked by the bios so you should try using these first.

On desktop motherboards, these limits are often times set sky high so they never become a limiting factor, especially when overclocking. I think the maximum possible number that can be used is 4095.

Anyway, set your Package Power Long limit to 35 and try setting the Short Package Power Limit to 35 or 40. If you use 40, reduce the Time Limit a little. There is no need to touch the PP0 Limits because the main one is unlocked. Also remember to use the Clamp option. This allows the CPU to reduce the multiplier to less than the default multiplier to make sure that your CPU package does not exceed 35 watts.

The Log File option includes power monitoring so turn that on and go play a game or run some benchmarks or whatever. The log will show you your CPU temperature as well as power consumption.

PS - Yep, same unclewebb as the guy on NBR.

Limit Reasons is a great little program that Dufus wrote. He is the brains behind some of ThrottleStop's more useful features so I thought it would be a nice gesture to include some of his work. This program shows why a 4th Gen Intel CPU is throttling. A yellow box means there has been some throttling since the CPU booted up. A Red box means that throttling is in progress. It is common to see some yellow boxes when the program first starts. Before testing, just click on the 3 headings, Core, Uncore and Ring to clear the previous results.

Some CPU models seem to have a minimum power setting that they can be set to. If you have any problems getting your desired results from the Package Power Limits, then try the separate Primary Plane Power Limits - PP0 setting.

Intel's 4th Gen CPUs get red hot instantly when running stress tests like Prime 95 which use the newer AVX2 instructions. These are powerful instructions but they create a huge amount of heat. Intel puts their core temperature sensors on the hottest spots on the core and when you start flowing a bunch of amps through a tiny piece of silicon, temperatures will shoot up instantly. As long as your CPU is not reaching the thermal throttling temperature which is usually set to 100C, no worries. Intel builds good stuff. If Intel was worried, they would lower the throttling temperature.

 

[Cerb]

I have not found any "target" TDP setting in Z97i-plus BIOS.

Should be right there.
http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/Z97I-PLUS/E9272_Z97I-PLUS.pdf
See page 3-23, starting with the feather.

 

[unclewebb]

You need to enable the Clamp option to make sure power consumption does not exceed 35 watts. It does not look like the Clamp option is available in the Asus bios.

 

[coercitiv]

Should be right there.
http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/Z97I-PLUS/E9272_Z97I-PLUS.pdf
See page 3-23, starting with the feather.

Oh boy, all this because OP hardly bothered to go through his own MB manual...

Long Duration Package Power Limit
Allows you to limit the Turbo Ratio’s time duration that exceeds the TDP (Thermal Design Power) for maximum performance. The values range from 1 W to 4096 W.

Package Power Time Window
Also known as Power Limit 1, this item allows you to maintain the time window for Turbo Ratio over TDP (Thermal Design Power).The values range from 1 to 127 in seconds.

Short Duration Package Power Limit
Also known as Power Limit 2, this item allows you to provide rapid protection when the package power exceeds the Power Limit 1. The values range from 1 W to 4096 W.