The Vishera Review: AMD FX-8350, FX-8320, FX-6300 and FX-4300 Tested
by Anand Lal Shimpi on October 23, 2012 12:00 AM EST
Power Consumption
With Vishera, AMD was in a difficult position: it had to drive performance up without blowing through its 125W TDP. As the Piledriver cores were designed to do just that, Vishera benefitted. Remember that Piledriver was predominantly built to take this new architecture into mobile. I went through the details of what makes Piledriver different from its predecessor (Bulldozer) but at as far as power consumption is concerned, AMD moved to a different type of flip-flop in Piledriver that increased complexity on the design/timing end but decreased active power considerably. Basically, it made more work for AMD but resulted in a more power efficient chip without moving to a dramatically different architecture or new process node.
In mobile, AMD used these power saving gains to put Piledriver in mobile APUs, a place where Bulldozer never went. We saw this with Trinity, and surprisingly enough it managed to outperform the previous Llano generation APUs while improving battery life. On desktops however, AMD used the power savings offered by Piledriver to drive clock speeds up, thus increasing performance, without increasing power consumption. Since peak power didn't go up, overall power efficiency actually improves with Vishera over Zambezi. The chart below illustrates total system power consumption while running both passes of the x264 HD (5.0.1) benchmark to illustrate my point:
In the first pass Vishera actually draws a little less power, but once we get to the heavier second encode pass the two curves are mostly indistinguishable (Vishera still drops below Zambezi regularly). Vishera uses its extra frequency and IPC tweaks to complete the task sooner, and drive down to idle power levels, thus saving energy overall. The picture doesn't look as good though if we toss Ivy Bridge into the mix. Intel's 77W Core i5 3570K is targeted by AMD as the FX-8350's natural competitor. The 8350 is priced lower and actually outperforms the 3570K in this test, but it draws significantly more power:
The platforms aren't entirely comparable, but Intel maintains a huge power advantage over AMD. With the move to 22nm, Intel dropped power consumption over an already more power efficient Sandy Bridge CPU at 32nm. While Intel drove power consumption lower, AMD kept it constant and drove performance higher. Even if we look at the FX-8320 and toss Sandy Bridge into the mix, the situation doesn't change dramatically:
Sandy Bridge obviously consumes more than Ivy Bridge, but the gap between a Vishera and any of the two Intel platforms is significant. As I mentioned earlier however, this particular test runs quicker on Vishera however the test would have to be much longer in order to really give AMD the overall efficiency advantage.
If we look at average power over the course of the two x264 encode passes, the results back up what we've seen above:
As more client PCs move towards smaller form factors, power consumption may become just as important as the single threaded performance gap. For those building in large cases this shouldn't be a problem, but for small form factor systems you'll want to go Ivy Bridge.
Note that idle power consumption can be competitive, but will obviously vary depending on the motherboard used (the Crosshair Formula V is hardly the lowest power AM3+ board available):
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c0d1f1ed - Tuesday, October 23, 2012 - link
Amdahl's Law is not a reason. There is plenty of task parallelism to exploit. The real issue is ROI, and there's two aspects to that. One is that multi-threaded development is freakishly hard. Unlike single-threaded development, you cannot know exactly what each thread is doing at any given time. You need to synchronised to make certain actions deterministic. But even then you can end up with race conditions if you're not careful. The current synchronization methods are just very primitive. Intel will fix that with Haswell. The TSX technology enables hardware lock elision and hardware transactional memory. Both will make the developer's life a lot easier, and also make synchronization more efficient.
The second aspect isn't about the costs but about the gains. It has taken quite a while for more than two cores to become the norm. So it just wasn't worth it for developers to go through all the pain of scalable fine-grained multi-threaded development if the average CPU is still only a dual-core. Haswell's TSX technology will come right in time as quad-core becomes mainstream. Also, Haswell will have phenomenal Hyper-Threading performance thanks to two nearly symmetrical sets of two integer execution units.
AMD needs to implement TSX and AVX2 sooner rather than later to stay in the market. Reply
CeriseCogburn - Tuesday, October 30, 2012 - link
Nice post. Appreciate it.And ouch for amd once again. Reply
surt - Tuesday, October 23, 2012 - link
No, gaming won't need that many threads in the near future either. Nobody is going to make a game demand more than 4 threads because that's what common gamer systems support. ReplyAnnihilatorX - Wednesday, October 24, 2012 - link
I disagree. Say we have a hypothetical game that support 8 threads. The overhead of over-threading in a quad core system is frankly, not very much, while it may provide improvements on people with octocore or Intel processors with hyper-threading. ReplyAnnihilatorX - Wednesday, October 24, 2012 - link
In fact, there are many games nowadays that split workload into many threads for economic simulation, background AI planning in user phase, physics, audio, graphics subthread, network management, preloading and resources management. It is just that even with the parallelism, there bound to be bottlenecks in single threading that a 8 core may not benefit at all compared to 4 cores.So I disagree, it is not about people not spending resources in making parallelism or not supporting it. It is the nature of the workload that is the determining factor. Reply
CeriseCogburn - Sunday, December 09, 2012 - link
LOL- amd sucks period, did you look at the gaming page ?these visheras got literally stomped to death
AMD fanboy = the imaginary, non existent, and never to exist future looks glorious for de furhor amd! Reply
redwarrior - Wednesday, October 24, 2012 - link
What a one dimensional computer enthusiast you are. You spend hundreds to play games on a computer when you could do the same ona console for less?? I use my computer to gain knowledge, impart knowledge, do organizing work to liberate the working class from wage slavery, write leaflets, an documents. I occasionally play strategy games that are usually multi-threaded, like Galactic Civilizations II. . There is no greater value on the planet than the FX processors for what I do. They save me time for the work I do over the Intel processor in the $200 price class. Time and money that's important , frame rates of a 120 are useless but too the over-privileged who buy 120 mhz monitors for their gaming. What a waste of money and resources that could be used for the advancement of human kind. Replybennyg - Thursday, October 25, 2012 - link
"Value" is more than just perf per purchase dollar, running costs also need to be included.E.g. a basic calculation based on the charts above the FX CPU I've saved $50 on would cost 2c extra per hour at full load in power. So 2500 hours at load would be my break even point. That's 7 hours a day at full load over a year, a heavy use scenario but quite possible.
Multithreaded games are such a vast exception to the rule (that once you have "enough" CPU power you gain infinitessimal fps from more) they are not worth even mentioning. Reply
redwarrior - Thursday, October 25, 2012 - link
You know NOT what you speak. Battlefield 3 is multithreaderd and look at AMD FX-8350 on Battlefield III - right up near the top, better than I 5 3570 and close to I7 3770. You guys are ignoring the facts and ignoring the trends in software. the move to parallelism is unstoppable and will accelerate. Multithreading is a growing presence and ONLY BAD programmers and software designers ignore it. The turning point will come when steamroller ships in a year and it will compete nicely with Hasbeen. At 28nm it will be almost as efficient as HasbeenPerformance wise it will be as good. Reply
CeriseCogburn - Tuesday, October 30, 2012 - link
LOL why am i not surprised, massive amd fanboy with chips on the shoulder, and a fantasy brain." o organizing work to liberate the working class from wage slavery"
LOL - perfect, just like the rest of the amd fruitballs. Have fun at the OWS protests, though it would have been decent to join up with Tea Party, instead of coming on a year plus late after all the complaining. (you brought up politics fanboy)
Anyway back to your fanboy fantasy. As I said, you can look all day long at the pileofcrap amd releases and tell yourself it's the greatest ball of cheese for you, but no one has to believe your bs. One big reason why.
SB 2500K oc's to 4500 like butter on stock everything, all 4 cores, all day and all night with zero hiccups, and blows the amd crap away period.
You actually have to be very stupid to not choose it. Very stupid.
Be aware fanboy, you're looking at stock 2500K in all the charts, and a clear +50% increase in instantly available with it, FOR FREE.
There is no way any amd fanboy made the correct decision after 2500K was released. And it's not occurring now either. You're living a lie, so please stop sharing it with us, and by the way - I don't think it's your place to tell others WHAT they can use their computer systems for.
THEY OWN THEM, not you. They are theirs, not yours, and you shouldn't be tooting your virgin purity hippy love angel wing CRAP here, and then also have the obnoxious insolence to tell others they are wasting their computer power.
There are plenty of people who will tell you flat out you are wasting your life and wrecking the nation with the crap you are doing, no doubt about it, so keep it to yourself, won't you ?
Now let's hear how your crapdirver amd can possibly match a 2500K in the real world...
LOL
ain't happening mister
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