Dell XPS 15 L521x Overheating

I was asked to take a look at a Dell XPS 15 L521x ultrabook because it was having video flicker problems. I originally took the approach of swapping out the thermal paste which helped a little, but the problem persisted. However, looking at the heatsink assembly, it was clear the problem wasn't the thermal paste, rather the heatpipe and heatsink is way too small for the Intel Core i7 and nVidia video processor. Remembering a similar issue with the HP Pavilion tx1000, the Dell XPS 15 L521x also had the heatpipe and parts of the heatfin covered in a black paint. I decided that it was time to scrub it off.

Before photo of the heatpipe and heatfin.

After photo of the heatpipe and heatfin. I scrubbed off the black paint using high isopropyl alcohol and a 800 grit sandpaper. A regular toothbrush had no effect on the paint. I had to use something a little more abrasive. The 800 grit sandpaper doesn't grind, it polishes. I use this particular sandpaper to polish down uneven heatsink surfaces. Even still, I couldn't get all the paint off.

To start things off, flip over the Dell XPS 15 L521x and lift the bottom metal plate. There are 2 screws hidden under there. Additionally, remove the screws around the edges of the bottom cover.

Once you remove the bottom cover, all the components of the laptop are exposed. There is a single ribbon cable connecting bottom cover to the main board. It's the battery indicator. In general, I leave that unhooked because it gets in the way and if you're like me and like to open up your laptop, the ribbon cable will get damaged eventually. The exposed pins on the ZIF (zero insertion force) ribbon cables lift off the ribbon surface from the act of inserting and removing the cable from the connector.

Below is a picture of the heatsink and fan assembly. Notice how the bottom half of the heatsink is painted black. Not entirely sure why, but based on my experience with the HP Pavilion tx1000, the black paint needs to be removed. See article regarding the black paint on the HP Paviliton tx1000 heatsink here on forum.tabletpcreview.com.

I had previously replaced the thermal compound with Arctic Silver 5.

Intel Core i7 processor

nVidia video processor

Close up of the painted portion of the heatsink.

Close up of the heatsink after scrubbing the black paint off.

The Dell XPS 15 L521x doesn't need a coppershin between the heatsink and the video processor because the connection here is very tight. Instead, I replaced the Arctic Silver 5 thermal paste and reattached the heatsink and fan assembly.

I fired up the system and decided to try to run the FurMark VGA stress test tool. FurMark might not be the best way to test a cooling solution because it puts unrealistic stress on the machine, but I did run the processor over 90 C and the video processor over 90 C for about 15 minutes and it held steady. All together, I ran FurMark for about 30 minutes. Additionally as a more realistic test, I ran a video encoding job that used to push the processor to over 90 C and it held stead at around 80 C. Overall, I would say that the cooling mod was successful.