Intel Core i9-9900KS - Overclocking And Power Consumption
We also spent some time overclocking the Core i9-9900KS using the Gigabyte Z390 Aorus Master motherboard and Corsair H80i v2, to see what kind of additional horsepower the processor had lurking under its hood...
As you would expect, overclocking a Core i9-9900KS processor is very similar to any other previous-gen Intel K-SKU processor. Because the processor is unlocked, overclocking it is simply a matter of altering a few multipliers, tweaking voltages, and dealing with the additional heat and power requirements. These processors can be overclocked by adjusting BCLK frequencies as well, so it's possible to really fine tune the end result, but manipulating the multipliers is where the big gains will come from.
We took a somewhat conservative approach to overclocking the Core i9-9900KS to give you all an approximate “worst case scenario”. Our results should be repeatable with most of the chips that end up out in the wild, assuming you’ve got similar hardware and everything is working properly. You shouldn’t need exotic cooling to pull off what we did here -- we used an off-the-shelf Corsair H80i AIO liquid cooler with the motherboard and processor installed in a mainstream NZXT mid-tower, with a couple of intake and exhaust fans.
During normal operation, we saw our Core i9-9900KS' voltage ratchet up to over 1.3v. So, to push things a little further and see what our sample could do, we manually cranked the core voltage up to 1.375v with a .05v offset and shot for a modest 5.1GHz (51x100MHz) all-core overclock and everything worked flawlessly. Next, we cranked up the multiplier to 52x across all cores, and again had no trouble at all. When we shot for 5.3GHz though, out test system became unstable and wasn't able to consistently loop taxing benchmarks like Cinebench. We attempted to increase the voltage further and increased it all the way up to 1.425v, which helped with stability, but the CPU would routinely shoot to over 100°C. Ultimately, we settled back down to 5.2GHz across all cores at 1.375v. Sustained use would still result in core temps in the high 90's, but the CPU didn't throttle and remained stable in our setup.
In its stock configuration, the Core i9-9900KS idled at around 33-35'C (give or take a coupe of degrees across the 8 cores) and peaked in the upper 70s. Even modestly overclocking the chip, however, immediately caused much higher temperatures with our mainstream liquid cooler. Intel is clearly pushing the limits of its 14nm++ process with the 8-core Core i9-9900KS and any significant overclocks are going to require some robust cooling.
That said, we were able to wring some additional performance from our chip. While we had the chip overclocked, we ran a few tests and saw some mild gains in the 3DMark Physics and Cinebench tests. But with only a 4% increase in the peak frequency, the boosts weren't going to be significant.
Throughout all of our benchmarking and testing, we also monitored how much power our Core i9-9900KS-based rig was consuming with a power meter, versus the other systems we used for benchmark comparisons.
Our goal was to give you an idea as to how much power each configuration used while idling at the Windows desktop and while under a heavy CPU workloads across one and all cores. Keep in mind, this is total system power consumption being measured at the outlet and not the the individual power being drawn by the CPUs alone.
We also monitored power while overclocking. With a relatively modest 200MHz increase to the max Turbo clock, we saw only an 11 Watt increase in peak power consumption. This (along with the additional power data above) tells us Intel is already pushing the limits of its manufacturing process and architecture with the Core i9-9900KS, so the modest bump in frequency we achieved didn't result in a giant upswing in power consumption. Note in the Cinebench screenshot above, package TDP while overclocked was listed at 215 watts.