Ryzen Release Thread

[SteelCrysis]

http://www.tomshardware.com/reviews/amd-...014-8.html

One of the lessons learned during the Ryzen 7 launch was that AMD's temperature sensor output has its share of problems. The company configured some of the models to report an additional 20°C on top of the actual temperature in order to guarantee adequate cooling. We’re still puzzled by this choice.

Nevertheless, we're accepting it as reality and going all-out on cooling for Ryzen 5's introduction. Alphacool offers a modified version of an industrial compression cooler under the name "Eiszeit 2000 Chiller." It has a powerful pump, and it’s compatible with the usual 1/4" connectors, thus making the technology accessible to enthusiasts like us.

We’re cooling the processors by connecting an Alphacool Eiszeit XPX CPU block directly to the Eiszeit 2000 Chiller. The compression cooler’s reservoir has a capacity of almost eight liters, serving double duty as a storage tank and compensating reservoir. This provides a large thermal buffer. At 40L per minute, the flow rate is high enough for our purposes as well.
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At first, we just wanted to see if we could explore how AMD's XFR feature behaved under perfect conditions, and how leakage current would compare to measurements taken with other cooling solutions. However, the first test run delivered a huge surprise:
At just under 17°C, the Ryzen 5 1500X’s reported Tctl temperature values at 19W total power consumption of the CPU package come in a full 3°C below the cooling fluid’s temperature of a constant 20°C!

We don’t really need to explain why these results can’t be correct. Consequently, we dug deep into our toolbox and found a liquid metal pad that was originally developed as a substitute for thermal paste. Our potent cooler kept the temperatures well below the pad’s melting point, so that it didn’t fuse with the processor’s heat spreader or the water block’s heat sink. We placed a thin strip between the heat spreader and the heat sink during our water-cooled measurements, making sure to cut the strip thin enough for it not to result in a measurable change in cooling performance. We used a tiny copper plate milled into a very thin strip for the stock cooler measurements.

The plan was simple: find the exact difference between the temperatures reported by the processor and the temperatures we measured for the processor’s heat spreader with the help of our constant cooling fluid temperature setup and infrared camera. Unfortunately, we found that the resulting differences between the temperature curves weren’t consistent and, consequently, still didn’t make any sense. There were two points at which the temperature curves changed drastically and clearly diverged from a linear pattern.

Based on these findings, we hypothesized that the behavior of the processors’ temperature sensors changed once certain temperature thresholds were reached. If this was the case, we could predict the sensors’ behavior for different temperature ranges and correct the temperature readings.

For our second round of testing, we compared the Tctl values to actual power consumption. A software tool developed in-house allowed us to generate different loads over long time periods, avoiding any jumps or delays that could skew the results. The tool would do its best to spread the loads equally across all possible threads. The results proved our previous hypothesis:
The reported temperatures are complete nonsense below ~20 to 25W. It’s also plain to see that there are significant differences between the Tctl reporting patterns of AMD’s Ryzen 5 and 7.
In general, we saw that upwards of 20 to 22W, there was a difference of approximately 4 to 6°C between AMD’s Ryzen 5 and 7 when using our cooling solution with its constant fluid temperature. The Ryzen 5 processors’ sensors consistently displayed higher temperature readings than the Ryzen 7 processors at the same power consumption level!

The additional 20°C that AMD builds into some of its Ryzen processor models are already taken into account in this calculation.

One more thing to consider is the potential difference in heat transfer between components for our particular cooling solution. Plugging in numbers based on our experience and then comparing the final figures to our infrared measurements yields the following results for the three wattage ranges:
Across the entire wattage range, the Ryzen 5 produces a difference of approximately 8°C. That's pretty significant. We ran several control tests and got the same results every time.

The next question is whether Ryzen 5's temperature displays too high, or if Ryzen 7 is too low by 4 to 6°C.

The following graph shows the CPU heat spreader’s temperatures over a time period of approximately 30 minutes in degrees Celsius. The Ryzen 7 1800X’s leakage current is approximately 58 to 60W. Comparing that to the curve in the graph above shows that Tctl and heat spreader temperatures should not be the same. The expected difference of approximately 3 to 5°C between the Tctl and heat spreader temperatures is reached by the Ryzen 5 1500X, though. These finding are consistent with what we thought.
The tentative bottom line seems to be that all Ryzen 7 processors report their temperatures as being approximately 4 to 6°C lower compared to the two Ryzen 5 processors at the same leakage current level.

The bend in the curve at approximately 50W becomes more interesting once we get to the gaming power consumption results. The smaller CPUs may stay in this range during gaming, which means that it might be beneficial to take our results into account when setting fan curves. Most people don’t have a compression cooler at home, after all. The lower your cooling performance, the more important it is to change sensor characteristics!

We measured the Ryzen 5 1500X with AMD's stock air cooler to illustrate our point further. Its fan was set to a fixed speed we chose after first running a stress test. The curve's two bends are easy to see in spite of the curves being much steeper. A closer look shows that the total power consumption increased by approximately 5W. This is due to increased leakage currents that accompany the much higher temperatures.

We stay with the temperature results a little while longer and take a look at all of the Ryzen processors’ temperatures. These are corrected for the temperature differences due to the three wattage ranges and the two processor lines.

Here’s a computational example for the Ryzen 7 1800X during the stress test:

67°C (Tctl, Sensor) - 20°C (AMD Ryzen Offset) + 4°C (Additional Offset for Ryzen 7) = 51°C

If you feel confused by all of this, then you’re certainly in good company. Nobody knows what prompted AMD to take the approach it did. If we didn’t use our offsets, then Ryzen 7 would be much cooler than Ryzen 5 at the same level of leakage current, which is physically impossible.

Before we close, we’d like to point out one more time that the temperature differences and offsets only apply to our particular test setup. Different hardware may very well affect behave some other way. The general principle shouldn’t change, though. A final judgement can’t be reached before these – admittedly elaborate – measurements have been repeated with a wide variety of setups.

Doing this just wasn’t possible under the time constraints of a product launch. The measurements took us three days for just the one setup.

http://www.tomshardware.com/reviews/amd-...14-11.html

Due to its identical clock rates, AMD's Ryzen 5 1600X demonstrates similar performance as the Ryzen 7 1800X in lightly-threaded content creation and productivity tests. The 1600X also outpaces the Ryzen 7 1700 in a great many scenarios where its higher frequency weighs heavier than its core count deficit. This makes the 1700 a tougher sell.

Intel’s Kaby Lake-based processors beat Ryzen 5 1600X in lightly-threaded applications where they can leverage superior IPC throughput. But the 1600X’s extra cores/threads turn the tables in software well-optimized for multi-core CPUs. Surprisingly, the 1600X even rivals the 1700X in certain scenarios. That paints a pretty convincing picture for a budget workstation chip, especially in light of the incredible price-to-performance ratio compared to Intel’s Broadwell-E line-up.

The Ryzen 5 1600X also makes a compelling argument against purchasing the 1700 for your next gaming PC. Six nimble cores regularly match or beat AMD's budget-oriented eight-core model. It'd be easy to speculate that, due to the 1600X’s lower core count, less inter-CCX traffic unburdens the Infinity Fabric and provides more competitive performance. We'll explore this in more depth later. For now, we think it's safe to say there's little reason for enthusiasts to splurge on the higher-end Ryzens for gaming, especially when the dual-CCX die overclocks similarly, regardless of configuration.

But don't forget the Core i5-7600K. It's a capable gaming processor. And although the 1600X challenges it in much of our benchmark suite, the Core i5 still comes out on top at stock settings. Further, overclocking Kaby Lake opens up a sizeable advantage that AMD cannot overcome, given limited frequency headroom. We expect Ryzen's overclocking potential to improve as GlobalFoundries' 14nm process evolves, but Intel's isn't sitting by idly, either.

AMD is still working on improving the utilization of Ryzen 5's resource-rich architecture, and a few gaming titles make it apparent that this is still a work in progress. We’ve seen several developers come forward with Ryzen-specific patches, and if AMD's gets its wish, more will follow suit. In the meantime, AMD developed its own Windows power profile to combat the performance issues we observed back when Ryzen 7 launched. Unfortunately, some of the other workarounds we played with may not apply as universally to Ryzen 5. For instance, disabling SMT on the 1600X resulted in choppy frame delivery, apparent in our frame time charts.

At least overclocking is allowed on inexpensive B350-based motherboards. This makes Ryzen 5 a much better value than Broadwell-E, arguably superior to Ryzen 7 for mainstream gamers, and at least competitive with Kaby Lake. As shown in our Infinity Fabric-oriented tests, though, you'll want a fast memory kit to achieve the best gaming performance.

Ryzen 5 1600X provides a tremendous price-to-performance ratio for budget workstations, rivaling Core i7-6800K. It also facilitates playable performance in games (though it still lags Kaby Lake-based Core i5s more often than not). Considering what Intel charges for its Core i5-7600K, we'd certainly like Ryzen 5 1600X a lot more for gaming if it debuted at a lower price. Much of the Ryzen tapestry is woven using value as its thread. But it's hard to keep that story together when Ryzen 5 1600X sells for $249 and Core i5-7600K goes for $240. With that said, professionals on a budget are far more likely to jump on a potent six-core chip like the 1600X when it's able to beat the $450 Core i7-6800K.