Disclaimer: This is done entirely at your own risk. You assume all responsibility for any damage done to CPUs. We will do our best to detail this process so that you can safely follow our steps, and following carefully will minimize risk. Ultimately, the risk exists primarily in (1) applying too much force or failing to level the CPU, both easily solved, or (2) applying liquid metal in a way that shorts components.

Still, given the $1000-$2000 cost with these CPUs, an error is an expensive one. We’ve put together a tutorial on the delid and liquid metal application process.

Running through the entire Skylake X lineup with TIM vs. liquid metal benchmarking means we’ve picked-up some very product-specific experience. Skylake X has a unique substrate composition wherein the upper substrate houses the silicon and some SMDs, with the lower substrate hosting the pads and some traces. This makes delidding unique as well, made easier with Der8auer’s Delide DieMate X (available in the US soon). This tutorial shows how to delid Intel Skylake X CPUs using the DieMate X, then how to apply liquid metal. We won't be covering re-sealing today.

How to Delid Intel Skylake CPUs (i9-7900X, 7960X, 7980XE)

Using Der8auer’s Delide DieMate X, the process is fairly straight forward:

Back-out the Allen key screw until it is not applying force to the lever. Place the CPU into the tray, aligning the CPU corner with the arrow to the DieMate’s arrow. The IHS should be facing up and out, leaving the SMDs on the bottom of the substrate visible through the underside of the DieMate. Ensure the CPU is resting level and flush. Apply hand force to the Allen screw until the delidder makes contact with the IHS. Keep a close eye on the RFID chip in the corner of the CPU (the black square) and compare its distance to the IHS as you progress. Once the IHS moves 0.5-1.0mm (it’ll be visible), it’s time to back-out the screw. You will likely need the Allen key for the final turn. Do not over-tighten. Far more damage can be done by over-tightening than the opposite. If you don’t tighten it enough, the lid won’t come off and you just re-do the screw work. If it’s over-tightened, the lid can smash capacitors and resistors underneath.

Der8auer’s tool is exceptionally easy to use and should largely guide itself. Once the IHS has moved slightly, it’s time to remove the CPU from the tray and manually remove the lid. You can do this by applying force up-and-out from the CPU, using only fingers to pull at the “handles” on the IHS. Do not apply rotational or lateral force in an attempt to break the silicone adhesive bond. The delid tool already did that – you must only pull upward, else risk ripping off SMDs on the CPU.

Note: If an SMD gets ripped off, don’t fear just yet. It is possible that it was only a capacitor, which means potentially some loss in ripple suppression or efficiency, but overall a still-functional CPU. We’ve done this and the CPU still works. Losing a resistor is much worse, and could result in a dead CPU. If a component shorts from liquid metal or accidentally gets removed/damaged, just clean everything carefully and re-test the CPU. It may still work fine.

Once the CPU and IHS are separated, we’d recommend removing the silicone adhesive (black glue) from the IHS, but you can leave the adhesive on the substrate for now. It will serve as a guide later. Removing the adhesive from the substrate will provide a slight thermal benefit (1-3C, from what Der8auer tells us), but is not necessary. We’d recommend leaving it on for a start, but it is important to remove the adhesive from the heatspreader.

How to Apply Liquid Metal

The danger of liquid metal is that it’s electrically conductive, which means that shorting components is easily done with too much. Using too little is also dangerous, as hotspots on the die might not reflect in software, but could silently kill the CPU.

We’d recommend applying a very thin film of liquid metal to both the IHS and the CPU surface. Check our video above for a good indication of how much to use and how much not to use – we show both.

Our recommendation is to use a clear nail polish to protect the capacitors and SMDs. This will create a thin film over electrically sensitive components to prevent shorts in the event of LM spilling over. From VSG of Thermal Bench, here is why nail polish works (and when it won’t):

"Nail polish typically has nitrocellulose or another functionalized cellulose in it which forms a thin, stable film without a gap over items such as fingernails, or the capacitors you used it over. An alkyl acetate helps move it into place, and then promptly evaporates leaving behind just the thin film.

"Some nail polish formulations have benzene derivates. Toluene is a prime candidate used by some companies, which does a similar job as nitrocellulose. Look at the composition before buying or using these, as toluene isn't nice to play with even at lower concentrations."

We find that it’s easier to point the syringe upward, then apply very gradual, slow force on the plunger. A single droplet should come out. Place this onto the CPU surface, then spread it with a cotton swab. Take any excess and apply it to the IHS underside, or tap into the plunger once again for more. Our video shows this process well and, as it requires some depth to see how the stuff spreads, we’d recommend watching it. Try applying liquid metal to a paper towel first, just for an idea of how it spreads.

If you’re seeing a pool and a ripple when moving the cotton swab, there’s way too much LM. You can use the syringe to siphon it back up, or rubbing alcohol and a paper towel to remove liquid metal. Liquid metal removal can also be done with a cotton swab that’s been dunked in rubbing alcohol.

Editorial: Steve Burke

Video: Andrew Coleman