Power Consumption And Temperatures
Direct Comparisons of Power Consumption
Similar to our performance numbers, we re-ran the 1800X review's power data to reflect the continual improvements being made to motherboard firmware.
Let's start by looking at idle power consumption. Intel's overclocked Core i7-6900K turns in a better result than the stock configuration because we also reduced the one-core Turbo Boost frequency.
The 95W AMD CPUs clearly use less power in our combined CAD benchmark. When we weigh average performance against power consumption, however, the eight-core CPUs from AMD and Intel are fairly similar.
The same story applies to our measurements in games, where Ryzen 7 blows away the Core i7s. It's been a long time since AMD was at least equal in terms of efficiency.
The 3.8 GHz Ryzen 7 sucks down more than 140W , but the Core i7-6900K is even worse at 166W. The Core i7-7700K down-clocked to the same frequency uses a conservative 86W or so.
Based on AMD's technology briefings, we know it has more granular control over clock rate. And it's notable that the 95W Ryzen 7 1700X we're reviewing today uses less power under our stress test than Intel's 91W Core i7-7700K. It takes a significant underclock to put the Kaby Lake flagship in first place.
We optimized our CPU cooler for Socket AM4 by using two nuts between the spring and bracket to increase force on the package to 0.4Nm. That is why these results differ from those in our launch article, where we only used washers.
The temperatures we recorded for the FX-9590 are a bit uncertain, since AMD’s older Bulldozer CPUs don't measure with 100% confidence. Moreover, the Ryzen 7 and Core i7 CPU readings aren't exactly comparable; both companies employ different sensor approaches.
Intel's Core i7-7700K is the only processor in our test field handicapped by cheap thermal paste between its die and heat spreader. Thankfully, AMD solders Ryzen's heat spreader, which results in good thermal transfer. This naturally shows up in the relationship between power converted to heat.
Enthusiasts should be happy with Ryzen's power consumption and its resulting waste heat.