Analysis of turbo restrictions and speed adjustments using Throttlestop.
Analysis of turbo restrictions and speed adjustments using Throttlestop.
Hi, I own a Dell G3 15 laptop equipped with an i7-9750H processor. Its base and boost frequencies sit at 2.6GHz/4.5GHz, with a TDP of 45W. Throughout my testing, I kept turbo boost disabled to maintain low temperatures. No undervolting was ever applied. By default, the CPU operates around 75-80°C during heavy workloads at 2.6GHz (25-30W) before dropping to roughly 1.3-1.7GHz. Initially, I suspected thermal throttling, but later I found that those temperatures weren’t high enough for it. If not for thermal limits, it might have been power or speed constraints.
So I investigated further. By default, both speedstep and speedshift were enabled in the BIOS. In ThrottleStop, the speedshift EPP checkbox was unchecked, yet the green SST indicator showed speedshift was active. Speedstep was also on in Throttlestop. However, in the TPL section, there was another checkbox for speedshift that was left unchecked.
1. Why do I see two different speedshift options—one in the initial window and one in the TPL section? What happens if both are enabled together? Which should I use? In the TPL section, PL1 and PL2 were both set to 90W. From what I understand, PL2 represents the maximum sustained power before a switch to PL1 occurs when turbo is active. If that’s accurate, then PL2 should be higher than PL1.
2. Why are PL1 and PL2 both at 90W? And can they actually cause power limit throttling when turbo boost is off and power draw is much lower than those numbers?
Regarding the testing: I simultaneously performed three actions. I disabled speedstep and speedshift from the BIOS, checked the “disable and lock turbo power limits” section, and also disabled PL2 in the TPL section as advised. I read that this would prevent any throttling. I expected to see a difference, but surprisingly, there was no throttling at all. The frequency remained steady at 2.6GHz, and temperatures stayed around 95°C. This confirmed that neither thermal nor power limits were acting.
When I re-enabled PL2 and removed the turbo lock box, the system behaved identically—no throttling, stable temps. This suggests that either speedstep or speedshift alone was responsible for keeping the frequency low. The confusion arises because both settings were at the same level, yet they didn’t trigger any limits.
Now I’m left wondering: what caused the throttling in the first place? Why isn’t the processor cooling down to a comfortable 90°C? I’d rather have some throttling than exceed 90°C. If anyone has insights or solutions for this situation, please let me know.
Some Dell laptops experience major throttling issues. When they overheat, instead of Intel’s thermal management handling the CPU, Dell introduced its own approach. This tactic backfires. Dell lowers the turbo power thresholds to an extremely low setting. As a result, serious power restrictions occur. Your processor might still run at 1.3 GHz during this phase. Many of these devices will continue throttling in this manner for a long time. This issue isn’t related to SpeedStep or Speed Shift. On newer models, the BIOS usually activates Speed Shift Technology automatically upon startup. If it does, the SST indicator appears green on the ThrottleStop main display. When you inspect the Speed Shift settings in the TPL window, this confirms Speed Shift is active and sends the correct minimum and maximum values to the CPU. If your BIOS handles this correctly, you shouldn’t need to check that option. I’m cautious—I always tick this box to verify the CPU’s Speed Shift configuration. On the main screen, there’s a Speed Shift EPP section. EPP stands for Energy Performance Preference, letting you choose between peak performance or maximum power efficiency. If you’re using Windows Power Plan Balanced, you shouldn’t activate EPP in ThrottleStop. Windows 10 can handle EPP itself. Open the FIVR window and review the monitoring table. As you adjust the system tray power slider, the Speed Shift EPP value should update accordingly. This simple method helps confirm Windows is applying the setting properly. To attempt a fix for Dell’s odd throttling, remove the DPTF driver and prevent it from being reinstalled. Search online for details about this driver and removal steps. Here’s additional info: https://bradshacks.com/disable-dptf/#:~:text=In Device Manager%2C find all,for this device