Boosting the Razer Blade Stealth 2019 (GTX 1650)
TL;DR (Unlock BIOS, edit IMON slope to 50, IMON offset to 3000, and IMON sign to -ve, void warranty)
Recently, I chanced upon the RBS (GTX) at 1499 USD during Razer’s Black Friday sale. With the laptop touted as one of the few ultraportables with a GTX1650 in a 13-inch form factor, the tech junkie in me promptly snapped it up.
The (relatively) weak CPU of this notebook has often been cited as the downside of this machine, with the CPU power throttled to 12W under load.
However, with a slight tweak to the bios (at the cost of voiding your warranty), the CPU performance can be improved tremendously.
Running Cinebench 20, the stock performance of the RBS GTX is only at ~1150, with the CPU being throttled to ~2.2 GHz to match the power limit. The temperature of the processor stayed around 70 degs.
The BIOS changes suggested by this article (originally for Razer Blade 15 with a 45W CPU) did indeed unlock the full potential of the RBS CPU. Before that, some BIOS editing is required.
By putting a mask on system readings for electrical current used by the CPU, the system is tricked into a lower power reading, and will continue to provide power to the CPU until the thermal/power limits are reached.
Originally, according to the stock power limit of 12W, the CPU(1065G7) voltage of ~1V, and P=VI, only around 12A of current goes to the CPU, limiting the operating frequency.
The article recommends setting IMON slope (S)to 50 (/100), IMON offset (O) to 31999 (/1000), and the IMON sign to negative.
This means that the P = VI equation is transformed to:
P = V ( (actual_I)*S - O )
Cinebench 20 performance jumped to ~2200, with the CPU running at ~3.5 GHz. Temps rose to 90 degs.
This set off alarm bells.
P is now reported to be 3W by the system. Substituting the IMON values, the actual_I turns out to be ~70A. The CPU is running at 70W for a 25W rated CPU!
Perhaps it will be wiser to run the CPU near it’s rated TDP. To do so, a recalculation of the current mask is required.
Since P starts throttling at 12W, we used it as the basis for recalculation.
12 = V*(actual_I)*S - V*O
With V*(actual_I) = 30W as our ideal limit and letting IMON slope to be 50:
O turns out to be 3 which means IMON offset is 3000.
By using the following config:
IMON slope: 50, IMON offset: 3000, IMON sign: -
The Cinebench 20 results are of ~1900, with CPU temps around a cozy 80 degs. This beats the typical results of a i7-1065G7, which is ~1800.
I also tested a game of DOTA 2 at High graphical settings with the Ranked Matchmaking AI Bots.
The system chugged along at 80 FPS and CPU temps were around 80 degs.
So pretty alright i guess?
(Battery life will suffer, so switch back to stock bios when travelling.)
