Apollo Lake (N3450) TDP limit gone after sleep under Window 10.

[Gormar]

After installing new GPU driver (15.46.02.4729) I noticed that putting device to sleep causes SoC not conform to TDP limit (6W).
For me it is quite fortunate because it is like free OC .



Warning.
Without active cooling it might be dangerous for SoC.

Can anyone confirm similar behavior. My device is VOYO V1 mini.

[bluesmanuk]

Does everything return to normal after a reboot?

Running at the full burst rate all the time would be useful if the processes in use all the time were taking advantage of them.

But as you say, dangerous without cooling and failure would likely be quite imminent.

[Gormar]

Yes, it will be back to normal 6W TDP limit after reboot or hibernation if you cut power to this box.

For me it is quite useful. 6W limit is a little to low for this SoC when ~2W is taken by IO and memory controller even on idle.

I just read that in the future there might be support for Apollo Lake in ThrottleStop application. That would resolve this issue for us all .

[bluesmanuk]

Is the driver from Voyo, Intel or a generic one from Microsoft?

Does it become a real speed demon when operating at full tilt?

[Gormar]

This is original Intel driver for IGP version 15.46. As for now "latest". I got it from there.

I wouldn't call it speed demon (I've got also [email protected] machine) but it became more snappy especially with more demanding or longer task like compressing/decompressing files in the background. Before after about 15 seconds running CPU/GPU heavy tasks it will clamp performance to 6W. Now it is almost free to perform up to 2.1GHz CPU and 600-700MHz GPU without throttling (besides thermal). It should behave like device with J3455 (10W TDP).

Even if I'm happy with this there is some catch. Without internal fan at full speed SoC will get to thermal limit quite fast (about 10 minutes of heavy workload). And I can not describe with words how annoying noise it will produce especially at night time .

[bluesmanuk]

Yes lol

The fan might well be annoying but might heat the house up in winter.

[Gormar]

I found how it happens but don't know why. It seems that MSR 0x610 is zeroed when going to sleep mode.

To set desired power limit you can use RW_everything application like this:

RW.exe /Min /Nologo /Stdout /Command="WRMSR 0x610 0x0 0x00DD8A00 0"

Where:
A00 is power limit 1 in this case equals to 10W (2560/256). Default is 600 = 6W (1536/256). 256 = 2^8 is first byte called PKG_POWER_SKU_UNIT from MSR 0x606 which in Apollo Lake case equals to 0x8.

Default over limit time is 28 second. You can change that knowing this formula:
Control Time Window = [(1+0.25*X)*2^Y]*Z

Where:
X is 23:22 bits from MSR 0x610, default = 3 (0x3)
Y is 21:17 bits from MSR 0x610, default = 14 (0xE)
Z is 19:16 bits from MSR 0x606 (Time Unit, default value = 10 (0xA) which equals to 1s/2^10 = ~976us)

Note: According to Intel Xenon E5 v2 series maximum Control Time Windows is 40 seconds.
For 40 seconds it will require: X=1, Y=15(0xF) = 2F when Z=10(0xA)
To place it into 23:17 bits of MSR 0x610 you need to shit that value 17 places left:
0x2F << 17 (0x11) = 0x5E0000.
When you connect that with power limit value [14:0] and power limit clamp [16] and enable [15] bits you will get:
0x5E000 OR 0x18A00 = 0x5F8A00 for 10W and ~40 second over limit.

More info about content of that register: https://groups.google.com/a/chromium...ns/2A3xVEEEc-I

[Gormar]

Right now you can use ThrottleStop 8.50 to change TDP limit of Apollo Lake SoC. No need to fight with the command line and RWEverything.

[mitchell4you]

Hmm..
Thanks for sharing.. I never heard of this tool..but it looks like a neat tool to have
(If you have proper cooling)