Temperatures: Stock Vs. Delidded Vs. Direct Die Cooling
With our platform built and the components prepared, it was time to quantify the thermal differences between delidding a CPU and replacing its thermal paste, and cooling the die directly. In each of the following charts, Without Modification means that no changes were made to the CPU; it's a stock sample. Delidded indicates that the processor's integrated heat spreader was removed and then replaced after using higher-quality thermal paste. Delidded and Cleaned means that we also took the time to remove Intel's adhesive residue, in addition to replacing its thermal compound with better stuff from our lab. Of course, the Direct Die entry corresponds to removing the IHS and mounting our thermal solution on the die itself.
The patent pending Skylake-X Direct Die Frame from overclocking champion. In this scenario the effectiveness of the CPU cooler is irrelevant due to the fact.
Establishing A Baseline
For our first pass, we stuck with default settings and tested the processor using three workloads. Cinebench R15 is one of the most common benchmarks for quantifying the effect of an overclock. It can utilize one core or all of them, and it's incredibly easy to run. We specified a static clock rate of 4000 MHz and dialed in a 1.06V supply voltage. Those parameters should be easily attainable by anyone.
As expected, the stock CPU with no modifications posted the highest temperatures. Delidding helped shave off 5 to 6°C on average, and cooling the die directly helps even more.
Prime95 v.26.6 does not utilize AVX instructions. But it's still one of the most taxing workloads you can hit a CPU with.
Our Core i9-7900X continued operating at 4000 MHz at 1.06V. Not surprisingly, the finishing order remains the same, though the impact of more effective cooling is amplified.
Switching over to Prime95 v.29.1 adds AVX instructions to the mix. The brutality of this workload automatically forced our CPU down to 3600 MHz at 1.0V (due to our CPU ratio offset of -4). But despite the more taxing benchmark, less aggressive clock rates and voltages lead to slightly lower temperatures than the preceding run without AVX support.
If we stopped benchmarking right there and had to draw a conclusion based on these results, we'd recommend leaving your Core i9 alone. The risk of damaging a $1000 CPU, voiding its warranty, and sinking money into extras like the delidding tool just aren't worth a slightly lower operating temperature. However, the gains become more significant once you start overclocking to higher frequencies.
The Impact of Overclocking
Next, we ran the same three workloads using higher clock rates and voltages. In our pursuit, we sought settings that put our chip's temperature as close to 100°C as possible.
In Cinebench R15, that meant a frequency of 4400 MHz at 1.25V. The overclock imposed significantly warmer temperatures, which increased from 46 to 75°C out of the box. And the delta grew as we improved the configuration's ability to dissipate heat quickly.
With or without adhesive, delidding facilitated gains of 11 to 12°C on average, but also reduced the hottest core's temperature by 15°C. Direct-die cooling helped even more, yielding an 18°C drop compared to the manufacturer’s stock heat sink and fan.
We used the same settings in Prime95 v.26.6 (without AVX), and were treated to significantly warmer temperatures. One core even got as hot as 96°C (never mind our high-performance water cooler and fairly modest 1.25V voltage setting). This is where we realized the benefit of delidding: gains of 15°C after replacing Intel's stock thermal paste and 22°C thanks to the Direct Die Frame are huge.
We had to lower the clock rate and voltage significantly under Prime95 v.29.1. At 4100 MHz and 1.15V, it was already getting worryingly close to our 100°C target. While executing AVX instructions is known to impose warmer temperatures, we've never seen anything like this. And the Core i9-7900X only has 10 cores. Just imagine the 18-core Core i9-7980XE!
MORE: Best CPUs
MORE: Intel & AMD Processor Hierarchy
MORE: All CPUs Content
A UK-based hobbyist started a Kickstarter campaign to bring his Ncore V1 water block to production. The V1 is designed to directly cool delidded processors and even has a delidding tool built into its bracket.
Every time a new processors comes out, people are quick to answer the question of “will it delid?” Non-soldered processors use thermal paste to bridge the gap between the CPU die and the underside of the IHS. Delidding is the act of removing the IHS to enable either direct cooling of the CPU die or replacing of the default thermal paste. The Ncore V1 water block is for either of those purposes.
The most striking thing about the V1 is its appearance. The block is smaller than the LGA 1151 retention bracket. In fact, the V1 fits within the retention bracket. Pressure is placed on the block from hinges built into the skeletal-looking frame. The mechanism is necessary because the CPU die is smaller than the IHS and may not sit directly beneath the centerpoint of the water block. The frame itself consists of a few parts that allow it to be transformed into a delidding tool. In this form, the bracket works on the same principle as other delidding tools. A lever applies shearing force to the IHS that breaks the adhesive.
The block’s other interesting features include an adjustable flow rate and the ability to be adapted for non-delidded processors. The explanation regarding the mechanism for adjusting the flow rate isn’t very clear, but it appears to work through a set screw. The block designer’s own testing shows the V1 outperforming a competing water block on non-delidded and delidded processors.
We don’t condone delidding unless you want to nuke your warranty, but even if you’re not feeling brave enough to take the plunge, the Ncore V1 is still a cool-looking and innovative water block for non-delidded processors. Currently, it supports only LGA 1151. You can back the project on Kickstarter starting from the equivalent of $7, but the cheapest option to acquire to water block is $97.