Need help understanding stuff like TDP

[Hold-Ma-Beer]

So, below is screenshot of a quick run of Cinebench R20 on my Asus Vivobook 14 equipped with a Ryzen 5 4500U. The charger is of 45W:

 

 

Looking at the CPU package power, it was 30W max. So I assume 30W is the TDP of my processor? As per AMD is should be 15W, but OEM can configure it from 12-25W.

Also, I've noticed that my CPU and iGPU can stay at much higher clocks at 70C (quite reasonable eh?) but drops quite significantly in longer loads (like you cans see here, at 14W)

Any way I could make it not do that?

Thank you!

[DreamCat04]

1 minute ago, Hold-Ma-Beer said:

So, below is screenshot of a quick run of Cinebench R20 on my Asus Vivobook 14 equipped with a Ryzen 5 4500U. The charger is of 45W:

 

 

Looking at the CPU package power, it was 30W max. So I assume 30W is the TDP of my processor? As per AMD is should be 15W, but OEM can configure it from 12-25W.

Also, I've noticed that my CPU and iGPU can stay at much higher clocks at 70C (quite reasonable eh?) but drops quite significantly in longer loads (like you cans see here, at 14W)

Any way I could make it not do that?

Thank you!

The TDP of U-class chips is 15W. Modern CPUs will boost much higher to make the experience snappy and they saturate the cooler like that. The lower wattage in long high loads is due to the boost time. Your cooler probably wouldn't be able to keep up with 30 watts of heat from your CPU, therefore it has a boost time that makes it not throttle. Also you wouldn't want a CPU drawing 30 watts on a presumably 45WH battery because that would mean that you'd only get 1.5h of battery life at max load

[Kilrah]

TDP is usually "what you have to plan for cooling long term", i.e. if you fully load the CPU for an extended period of time that's the amount of heat to get rid of. Doesn't mean that it won't go higher, sometimes significantly so by boosting for shorter periods of time if the conditions (temp, power delivery, OEM BIOS configuration) allow for it.

 

You can play with it using AATU on Ryzen chips.

[Hold-Ma-Beer]

6 hours ago, Kilrah said:

TDP is usually "what you have to plan for cooling long term", i.e. if you fully load the CPU for an extended period of time that's the amount of heat to get rid of. Doesn't mean that it won't go higher, sometimes significantly so by boosting for shorter periods of time if the conditions (temp, power delivery, OEM BIOS configuration) allow for it.

 

You can play with it using AATU on Ryzen chips.

Whats AATU? 

Also, does Ryzen controller work on asus vivobook lineup? I saw somewhere something about undervolting laptop APU can help with thermals and overll performance... Is it worth it?

[Kilrah]

12 minutes ago, Hold-Ma-Beer said:

Whats AATU? 

Modernized version of Ryzen Controller. https://github.com/JamesCJ60/AMD-APU-Tuning-Utility/releases

[Mister Woof]

Don't feel bad. None of the tech companies can agree to measure it the same way either. So confusion is normal.

 

 

[Hold-Ma-Beer]

Sorry for mentioning y'all, but I need some more help.

As @Kilrahmentioned, I tried AATU. I set the TDP, long and short boost to 20W. This is my config:

 

When I started playing, I noticed drop in performance after around 30 mins. I opened up HWINFO64 to check clocks and power usage and the battery section caught my attention. I saw charge rate at -3.4W at load when I was plugged in! Should this happen?

My laptop has a 45W charger, and I dont think 20W taken by my APU will force the rest of system to drain my battery.

Battery was at 80% when I started and went to 78 when I noticed...

Here's a screenshot I took later.. I had to restart HWINFO64 cuz I closed it accidentally..

Thank you!

@Shimmy Gummi@DreamCat04

 

[Kilrah]

20W is the APU only, there will be the display, motherboard, drive, and probably another 10-20% of that all on top due to power supply efficiency. Also the power circuitry might have a cap and not be able to supply more than X and limit itself to that.

 

Also you need to look at the detailed temps in HwInfo that we haven't seen, on some laptops like mine it's the "skin temp limit" that's the one that ultimately causes throttling. So see if the Skin Temp plateaus at some point and that coincides with the drop in performance, if so you may want to try adjusting that.