Jesper Berg Intel’s Raptor Lake CPUs offer a great deal of performance for the money, but this comes at the cost of high power consumption and heat. Even if you are not overclocking, the 13700K and 13900K will inevitably run into their TjMax temperature limits and start throttling during extended all-core loads. This will happen even with the best coolers, only later and the effect will be less pronounced. With that in mind, undervolting with the goal of improving efficiency seems like a reasonable idea for many use cases.
Why BIOS instead of Intel XTU?
The easiest way to undervolt and/or overclock your Intel CPU is by using Intel’s Extreme Tuning Utility (XTU), which is admittedly a powerful and user-friendly piece of software. Unfortunately, this requires you to disable the Hyper-V virtualization functionality and the (also virtualization-related) Core isolation security setting in Windows. Otherwise, this will prevent XTU from getting the low-level hardware access it needs for you to tinker with the processor settings.
Disabling virtualization altogether will obviously be out of the question for anyone who uses virtual machines (VMs) on a regular basis. Microsoft’s Core isolation security option is a more contentious topic, but that’s another discussion.
You may also have other reasons to take the BIOS route over XTU, such as running Linux instead of Windows, or simply wanting to ensure that your (comprehensively tested and stable) settings stay with you through major OS updates. In any event, it’s a more semi-permanent solution.
MSI Z790 Carbon BIOS Settings
In this example, we are using a system consisting of an MSI Z790 Carbon WiFi motherboard, a Core i7 13700KF (13700K with integrated graphics disabled) cooled by a Cooler Master ML120L V2 AIO, 32 GB of 6000 MHz DDR5 (CL36), and a 2TB 990 PRO SSD. The GPU is an RTX 3080 10GB. No changes will be made other than a -100 mV voltage offset.
After pressing the Delete button during boot to enter the BIOS, the first step is switching to ‘Advanced’ mode via the top-center button.
Next up is the ‘OC’ section of the BIOS, which contains all options related to CPU and DRAM voltage, clocks, timings, etc.
After scrolling down a bit, the CPU voltage settings can be found in the menu with the same name. We ended up with the following settings:
- CPU Core Voltage Mode: [Adaptive + Offset]
- CPU Core Voltage: [Auto]
- CPU Core Voltage Offset Mode: [-]
- CPU Core Voltage Offset. [0.100]
Using the ‘Offset’ alternative should mean that the voltage (0.1 or 100 millivolts) in the corresponding menu item is added to (or in this case, subtracted from) stock settings, but the voltage will still be allowed to adjust dynamically.
Basic Undervolt Results: Benchmarks
What you expect from simply lowering the voltage is that the CPU manages to run cooler and more efficiently. This might be an end in itself in a laptop, but not so much in a gaming PC or workstation where you also want to maximize performance – or at the very least not lose performance by going overboard with the voltage reduction.
Cinebench is a rendering test and is not representative of most other types of workloads such as gaming. The multi-core test is nevertheless interesting, as it shows how your CPU and cooler combination handles an all-core maximum load. Our struggling single-fan AIO gets a bit more breathing room with the lower voltage. The higher score is easily explained by looking at the clock speeds after a few warmup loops:
With the lower voltage, the P-cores are able to consistently run at about 150 MHz higher speeds in this case. The E-cores are also slightly boosted.
The same tendency can be seen in 3DMark’s CPU Profile benchmark, which is much shorter (not looped) and therefore less dependent on the cooling capacity. Improvements are only seen at higher thread counts, while the difference is negligible with four or fewer threads.
That’s it for this simple undervolting experiment, and it seems to confirm that it is something worth looking into if you want to improve multi-core performance –especially if your CPU cooler is on the weak side.
