Without some hardware and software tweaks, your brand-new XPS 15 won’t be able to perform anywhere near its potential due to throttling.
Before you begin the journey of optimizing your XPS 15, you’ll want the following: 1.5mm 6.0W/mK thermal pads, Thermal Grizzly Kryonaut (best thermal paste at the moment without resorting to the liquid metal variants), some highly pure rubbing alcohol and some microfiber cloths.
As mentioned in our detailed review, the XPS 15 9560 with the Core i7-7700HQ processor is prone to two types of throttling:
- Thermal throttling of the CPU or GPU (generally the CPU) when temperatures get too high
- Voltage Regulator Module (VRM) throttling caused by it getting too hot and being unable to deliver enough power
The first type of throttling is quite straightforward to all but the most uninitiated: the CPU and GPU have temperature limits to prevent damage. Exceeding the temperature max (100C for CPU, 97C for GPU) will cause an instantaneous shutdown—but you should never see temperatures anywhere near that as the components will throttle their performance long before they get to that point.
There are softer limits than 100C and 97C for the CPU and GPU respectively, however. The GPU will reduce its clocks to keep its temperature below 78C, and the CPU will dynamically reduce its turbo-clocks based on temperatures and power consumption.
The second type of throttling is also the result of heat, but because people generally look at CPU and GPU temperatures alone when benchmarking, it went undetected for a long time.
The VRM’s job is to convert 5 or 12V power from the adapter or battery into much smaller voltages to feed the CPU and GPU (generally 1.5v or less). A VRM has several components, but we are primarily interested in only two: MOSFETS (short for metal-oxide semiconductor field-effect transistor, but you don’t need to know that for any reason except trivia) and chokes. The MOSFET is responsible for switching the voltage down to a manageable level to feed the CPU and GPU; the chokes stabilize the current.
In this image (courtesy of iunlock of Notebookreview), the MOSFETs and chokes have been identified with their temperatures under load. Throttling occurs around 78C.
To get your XPS 15 to run at its maximum potential, we will need to solve both these problems. First, let’s take care of the CPU and GPU heat directly. For this, you’ll need your Grizzly Kryonaut, 99% rubbing alcohol, and those microfiber cloths.
- Use a T5 screwdriver to remove the 10 Torx screws around the edges of the bottom panel.
- Open the service hatch and use a Phillips screwdriver to remove the two Phillips-head screws.
- If this is your first time opening your XPS 15, it will take a bit of effort to take the bottom plate off, as there are many small clips that keep it attached. Get your fingernails or a plastic card under the sides of the base near the hinge where the casing is most robust, and apply even, steady pressure to pull the bottom off.
- Remove the battery connector by pulling gently.
- Use your Phillips screwdriver to remove the five screws of the heat sink assembly.
- DO NOT PULL ON THE PIPES TO REMOVE IT. The heat sink assembly bends very easily. Carefully remove the heat sink assembly by getting your fingers under the upper edges of the left square (this is the GPU’s heat spreader) and gentle pulling upward on the top edge. The assembly should come up fairly easily once you overcome the glue-like suction of Dell’s abominable paste-job.
- Use the microfiber with the rubbing alcohol to remove the existing thermal paste. You’ll want to clean both the CPU and GPU dies as well as the heat spreader. Keep cleaning with the alcohol until you don’t see any grey marks on the cloth after rubbing.
- Put a little (half the size of a grain of rice) dollop of the thermal paste onto each die. Don’t worry, it will be pressed flat by the pressure of the heat spreader.
- Carefully replace the heat sink assembly flat onto the dies. Keep applying firm downward pressure over the heat spreader areas with one hand while you reinsert the screws with the other.
- Tighten each screw only a little at a time, taking turns tightening the screw diagonal to it so the pressure on the heatsink is uniform.
- Reconnect the battery.
- Place the bottom case cover back on the unit. No need to screw it back on yet, though.
- Turn on your laptop and run some tests! If you’ve done it right, you’ll see a pretty good reduction in CPU and GPU operating temperatures.
The next step is using software called ThrottleStop to reduce the power consumption of your CPU. This can reduce the load wattage needed for the CPU by 10W easily.
Generally, all the i7-7700HQs on XPS 15 9560’s I’ve seen can undervolt to -125mv for core and cache. I run -125mv on core/care and -75mv on the iGPU.
The final tweak to take care of your CPU and GPU temperatures is to go to the Nvidia Control Panel and change the “Maximum pre-rendered frames” value to “2”. This will prevent the CPU from needlessly being overtaxed to send data to the GPU.
The next step is dealing with the temperatures of the VRM head-on. Take another look at this picture:
Our goal is to cool those MOSFETs with the highest temperature (above the heat spreader) so they don’t hit their throttling temperature. How? We will be using stacked thermal pads to connect the MOSFET to the aluminum bottom cover. Why? When the right type of pads are used, the bottom cover will wick heat away from the MOSFETs.
There is trick to this, and it explains why we use lower performing 6W/mK thermal pads instead of some very high quality ones: if too much heat is transferred to the case it will actually end up heating up the VRM instead of cooling it. This is what will happen if you use an extremely conductive (16W/mK) thermal pad, and it’s why we want the 6W/mK pads for this purpose instead.
The mod is fairly straightforward: cut out small vertical strips from the thermal pad and place them on top of the MOSFETs above the heat spreaders. If you are using 1.5mm thick thermal pads, you will need to stack 3 of them on top of each other in order to reach the case. You want to leave as much open space around the pads so what little airflow there is doesn’t get impeded.
That’s it! Once you have stacked your little padded pillars over the MOSFETs and put the case bottom back on, you should be able to run any game or benchmark without VRM-induced throttling.
After following this guide, your Dell XPS 15 9560 should now be a finely tuned beast of a machine, able to leap mountains in a single bound. If this guide helped you, please let me know in the comments and share this guide.