source：http://wccftech.com/article/radeon-rx-480-reducing-voltage-increasing-efficiency/
自翻，转载请注明出处。
On June 29th 2016 AMD officially launched the Radeon RX 480 and many people, including myself, snagged up one for themselves before they were sold out. After seeing what Nvidia’s Pascal architecture was able to achieve in term of power draw and overclocking I was eager to see what was capable with AMD’s smaller 14nm GPU, hoping for better overclocking than what the R9 Fury X was able to deliver and hoping maybe some of the high overclocks that were being reported ahead of launch were correct.
【今年6月29号，AMD正式发布RX 480。然后很多人，包括我自己，在它卖完之前抢了一张。在看到Nvidia Pascal架构在功耗和超频上的巨大成就后，我很想看看AMD的14nm小核心能做到什么地步，希望它的超频潜力能比FuryX大。】
Then the reviews started rolling out about the same time I placed my order. That’s where things got a bit interesting. Almost every reviewer were mentioning very poor overclocking, even the ones that tried to make it sound not-so-bad were only getting a few percentage in terms of frequency increase. In the process of overclocking and what it took to get there the reviewers were finding that the power draw was increasing substantially, well past the point of what most consider being ‘safe’. I have to be perfectly honest; I was extremely disappointed by this.
【然后我刚下单就有一堆评测出来了。然后事态变得有趣起来。几乎每个评测的都说超频能力很渣，个别嘴下留情的也只能超几个百分点。在超频过程中很多人都发现功耗大幅增加，远远超过了能够接受的幅度。说实话，我很桑心。】
However, there was a beacon of hope, I did not order the more expensive cards I instead went for the modest $199 4GB model from XFX. After all that’s the price point that was most enticing to many readers and with the only variation from the 8GB model being memory capacity and a slight down-tick in memory speed, it seemed like the best value card. There was good news that came out of the less than impressive overclocking results, and that was that it yielded so little benefit that it is arguably a pointless endeavor.
【然而，还是有希望的。我没买8GB版，而是买的XFX的199刀 4GB版。毕竟这才是对所有玩家诱惑力最大的价位，4G版虽然比8G版容量小了，显存频率稍稍降低，但它依然是最值得买的。】
But how is that good news? Easy, the card was performing great, much better than anything else at $199 and (so far in my testing) as fast as my beefy 8GB XFX R9 390. I had already gotten several aftermarket cooling solutions to see just how much extra performance we could get out of it, seeing that was a pointless journey I sat all of those to the side after getting my card in the mail the next day. I found that my card wasn’t anything special, it only got up to around 1320MHz on the core and temperatures went wild in the process cresting 90c easily. The total system power draw I was seeing while running sat my RX 480 right between the EVGA GTX 960 SSC and the XFX R9 380 OC, which while better in terms of performance per watt, was still a bit higher than expected.
【那么好消息是什么呢？很简单，这张卡性能很棒，比目前任何199刀价位上的卡都要强，和我的8GB XFX R9 390一样快。我原来已经准备好了几个非公散热来测试极限超频性能，但在我拿到真卡测试之后我发现这都是无用功。我的卡没什么特别，只能超到大概1320Mhz，并且温度很容易就飙上90度。整机功耗在EVGA GTX 960 SSC 和XFX R9 380 OC之间，能耗比预计的好点。】
So what do you do when the performance is already really good out of the box and you can’t really get anything out of it by overclocking? You underclock it right? NO. You take the power levels down to the lowest level without losing any performance so that you greatly increase efficiency, but to do so without losing any performance.
【如果艹不上去的话你会怎么做？马上解锁电压？不。你可以降低电压，同时不损失任何性能，同时提升效能。】
In the past this required the use of 3rd party applications like MSI Afterburner to take control of the voltage and power limit of the GPU core, but with the release of the RX 480 AMD has seen fit to toss out Overdrive in favor of their new WattMan software. No, no superhero but it is a super tool for the average Joe. Giving us access to several P-States and allowing us to manual set the voltages at the higher end of the performance target, we could potentially reduce the power draw of the GPU and still have the same effective performance.
【过去需要用微星的Afterburner来控制GPU电压，但随着RX480的发布，AMD把Overdrive分离出来，做成了新的WattMan。虽然它不是某个新的超级英雄，但是它对于小白来说是很好的工具。可以控制几个功耗状态，并且允许手动控制电压】
Stock【默频】
Going into Wattman within Radeon Settings, we simply set the Voltage to manual control and adjust the final two P States down slightly.
【进到WattMan，手动控制电压并稍微降低最后两个功耗状态】
Undervolt【降压】
It doesn’t take much with GPUs to be effective, but you can get experimental and maybe drop your voltages even lower. There have been reports of people lowering the voltages and getting better overclocking results over on reddit.【很快设置就生效了，但你也可以试试更低的电压。在reddit上有人降低电压并且取得了更好的超频成绩。】
测试平台
Core i7 6800k stock【6800K默频】
32GB (4x8GB) Corsair Vengeance LPX DDR4 2400MHz【4X8GB 海盗船 复仇者LPX DDR4 2400Mhz】
Asus X99A-II【华硕 X99A-II】
Cooler Master V1200Platinum PSU【酷冷至尊 V1200Platinum】
XFX Radeon RX 480 4GB【XFX RX 480 4GB】
We took the total system power draw from the wall using a Kill-A-Watt after running Unigine Valley for 30 minutes.
【运行UnigineValley 30分钟，使用功率计测量整机功耗】
But none of this matters if we lose performance, because this entire point of this was to keep our performance but ditch some leakage and over use of power. So how did we come out? Not too bad, see for yourself.
【就算掉点性能也没关系，因为我们的目标是保持性能并降低漏电和过高的功耗。那么结果如何？不算太坏，自己看吧】
Throughout 3DMark Firestrike and Unigine Valley we saw no negative change in performance, if anything they improved in Firestrike. We were able to maintain the 1266mhz boost clock even with it being undervolted slightly and see varying degrees of improvement. Temperature being reduced by 1c may not look impressive, but you see that the fan is now spinning at 44% instead of 50% reducing noise leves. We also see that the GPU power draw is more in line with what we were expecting based on the 110w GPU Core power Draw claim, coming in at 112.5w versus the stocks 124.2w. Lastly we see a drop in maximum voltage delivered to the card, coming in now at .9875v vs the stock 1.0375v, and that’s the magic that made all of this happen.
【在3DMark Firestrike和UnigineValley中没有看到对性能的负面影响，除非他们对Firestrike做了针对优化。即便是降低了电压，我们仍然能保持1266Mhz的Boost频率，还能看到一点点性能提升。温度降了1度，看起来没什么卵用，但转速为44%而不是50%，噪音有减少。同时GPU核心功耗为112.5W，更加符合当初声称的110W。（默认为124.2W）最后我们看到最大电压从1.0375V降低到0.9875V，这就是原因。】
