Atom x5 z8300: Agressive throttling with video on 4k display

Hi...

This is something quite strange. I have this HP x2 210 (one of those 2-in-1 convertibles) which has an Atom x5 z8300. Apparently it's throttled to 1.60 GHz, that's the max it goes under stress. Sometimes it goes up to 1.7x but immediately falls back to 1.60.

Well, 1.60 is enough for me. The thing plays video well, with HW decoding it doesn't break a sweat even with heavy bitrate 4k h264... as long as you watch it at 1080p or less.

And there's the problem. I connect the HDMI to my 4k display (HDMI on the Atom is 1.4 so 30hz is as far as it goes), matching the frequency to the fps of the content I'll be watching, usually 24 fps, so 24hz. If I keep the player window small it plays full speed, with ~50% CPU usage at ~1.20 Ghz. Great. But as soon as I maximize the window or go full screen I get 15-18 fps playback and the CPU gets stuck at exactly 0.48 GHz.

I'm using PotPlayer and no matter what settings I change, using ffmpeg, quicksync, resizer, using fullscreen exclusive mode, nothing matters. I went to the power options and disabled EVERY power saving feature I saw. I also set the minimum CPU frequency at 100% and, as expected, it runs at 1.60GHz all the time. EXCEPT when I make the video playing window bigger or go full screen. I plugged it in, restarted, shut it down, nothing. As soon as the player window gets bigger than around 1920x1080 the CPU drops to 0.48.

I've read somewhere that when the GPU is taxed on these things the CPU throttles accordingly to allow more power to the GPU. That would explain this more or less. But even then it seems that processing the ouput for a 4k display is too much and the poor CPU can't help at 0.48. Any ideas?

I've read reviews of this chip and everyone says it plays 4k and all but I haven't seen any about anyone using it on an actual 4k display.



P.S.: I just tried ThrottleStop. It seems the above is the case. When making the window bigger the "package power" jumps from 5W to 7.5W (it stays at 1.5-2W while idling with the processor at 1.60, playing video in a small screen makes the TDP jump to 4.5-5W, maximize the window and it tops at exactly 7.5, not a 0.1W more). I thought the TDP of the Atom was 2W? Temperature raises to 75 also, two of the cores max at 79 degrees while at 7.5W.

While at 5W the CPU works at any speed, but as it jumps to 7.5W it drops to 0.48, all that power must be going to the GPU then. Playing something while trying to output 3840x2160 must be more than this darn thing can do. A pity, it could had made a terrific 4k media player


Edit: Trying a few times more, for about five or seven seconds I got 4k playing fullscreen smoothly without the CPU stepping back. After those seconds it went straight to 0.48 and playback suffered. This further confirms (or so I believe) it's not software, but hardware, the Atom, bios, the way HP made this thing, something is holding it back

I couldn't repeat the experience, those seconds were like magic (?)

 

Playing 4k video with an Atom is a bit of a pipe dream... My 3940xm couldn't run 4k video without stuttering, the 4790K that I got finally could play 4K video properly..

Sent from my LG-H850 using Tapatalk

 

Make sure BD PROCHOT is not checked in ThrottleStop. Also post a few ThrottleStop pics so I can see some more info about this CPU. The TPL window might have some info in there that is interesting.

Intel lists that this processor has a Scenario Design Power (SDP) of 2 W. That is not the same as a TDP rating of 2 W. Intel's low power CPUs are designed to burst to full speed but only for very short periods of time. A few adjustments in ThrottleStop might be able to help a little but there is only so much you can do with a low power CPU.

 

Yeah, it's just a pity that it *can* play 4k video easily but *can't* display it in a 4k screen. Not even 1080p content on a 4k screen, anything is too much to display at such big resolution it seems. Still, I can stream 4k or watch a 4k file on the tablet screen without having to reencode and that's useful enough.

Btw, regarding playback I manage to get a few FPS more using the "overlay mixer" which appears to be the simplest renderer out there (but it looks worse). The CPU manages to clock at 700-800 MHz but I still don't get the full 24 fps. Just a little shy of it, at around 19-20 fps.

Thanks for dropping by. The BD PROCHOT is not checked, but it's greyed out. I don't see any option to turn it on like the guide says. Am I missing something?





Those are while idling. Note that it idles around 500-700MHz (7-8 x 80MHz) and that's with the balanced power profile. When it goes to 480 (6 x 80) it's going to the absolute minimum it can do (even when I manually set everything to be performance oriented in the Windows' power options). There's no doubt it throttles to give power to the GPU. Otherwise it never stays constant at the absolute low, even with every power saving option on.

Regarding the clock speeds, if the CPU has usage peaks you can see it climbing to 1.70 or 1.80 GHz, but only with peaks (a sec or two tops). Any sustained load will see it topping at 1.60. This must be a manufacture setting I guess, since Intel ratings are 1.44 normal and 1.84 turbo. At least I get 1.60 sustained, it doesn't drop even after a long while, temp is around 60-65C, package power about 5W. I'm not complaining, it's like forget about turbo and have a regular 1.60 CPU, that works well. Too bad about the power limits crippling the CPU when the GPU is at heavy load (the only time I see it hitting 7.5W power)

If you have anything I should set in ThrottleStop or any other screen I'll be glad to try (as long as it doesn't fry the little Atom )

 

Turbo boost is not designed to give you full boost when both or all cores are active. The amount of boost is automatically reduced based on how many cores are active. That is by Intel design and cannot be changed.

Post a screenshot of the TPL window. There might be a few things in there that can help the cause if your bios did not lock them. The max power limit is shared by the Intel CPU and Intel GPU. When you go over the max limit, both can throttle.

No guarantees! If you cannot afford a new one, you shouldn't push what you have to the limit. I think that is just common sense.

Edit - The BD PROCHOT option is not available on your CPU. Put a check mark in the Set Multiplier option and max that out.