08-27-2019 04:06 AM - edited 08-27-2019 04:07 AM
My T490 has the same symptoms.
If you work with the CPU and the GPU, the power that the CPU uses will be rapidly generated and fixed at 6W.
Under these circumstances, the CPU cannot function with a proper clock.
I don't think this is normal behavior.
But I don't think we can cure these symptoms without Lenovo's interest.
08-27-2019 06:05 AM
After switched to max power mode, PL1 and PL2 will be set to 25W. Then I ran FurMark to burn GPU only, PL1 automatically dropped fast and locked at 6W at the end. It was the key point. But why? And how to avoid it?
08-27-2019 06:17 AM
Maybe even with GPU, the CPU temperature goes up with the limits of the cooling system, and we're limiting it to prevent this phenomenon.
But even if this is correct, I think the 6W limit is too severe.
I've been looking for a number of ways, but I can't find a clear solution.
08-27-2019 06:42 AM - edited 08-27-2019 06:45 AM
I (and probably most of the T490 + Nvidia MX250 users) would like to request further investigation of this issue by an engineer who is involved in Lenovo Thermal / Throttling / BIOS development.
I tried to figure out to contact the people who are in charge of the development of BIOS/ECP, but it seems almost impossible until Lenovo Staff in this forum forwards user issue to them.
Please, please don't regard this problem as regular throttling (@Jwes_Lenovo, @someotherguy). If you are Lenovo Staff and if you don't know how severe it is, PLEASE forward this issue directly to actual Lenovo development department for investigation.
Hope next BIOS/ECP update fixes this issue.
08-27-2019 06:57 AM - edited 08-27-2019 07:03 AM
I could find some clues in the NotebookCheck review.
It was found in the review of T490 and T590 with MX250 as the top.
In the case of T490 which was reviewed in May, the power of the CPU was maintained steadily at 10W even under GPU load, but in the review of T590 which was reviewed in July, CPU power was maintained at 6W and was not recovered.
The T490 and T590 use the same BIOS, and that's enough time for a two-month period to be BIOS Version updated.
Maybe later on, the BIOS that came out got a bug, but I think they know they don't recognize it.
I'd like to have Lenovo staff at the forum communicate these issues, if possible.
08-27-2019 10:43 PM
It's an old issue even found on T480 with MX150 as below:
Lenovo had plenty of time to notice and fix it. But after more than a year, they did nothing.
08-27-2019 11:43 PM
I saw the post with the link and understood it.
There was the same problem with T480 and Lenovo was very disappointed that he had been in neglect and not fixed for a year.
Lenovo employees would like to ask if they use these restrictions as normal.
I chose GPU option to use stronger performance than the internal graphics, and if this is the case, I'm annoyed that it's just a dime, and I won't buy a ThinkPad next time.
08-28-2019 04:12 AM
I found a clue in Reddit.
There was a user saying that when the GPU temperature of T480 reaches 70°C, the power of the CPU continues to go down.
To avoid these restrictions, it is important to keep the GPU temperature below 70 degrees.
But I don't want to be stressed by the temperature in a laptop I bought for a considerable amount of money.
I don't know why Lenovo forces us to do this.
08-28-2019 04:49 AM
I found a solution.
Use Throttlestop, in the FIVR function, enable "Disable and lock Turbo Power Limits".
After that, PL1 & PL2 was really stable during my half-hour burning test on both CPU & GPU.