AMD Bulldozer / FX-8150 Desktop Performance Review

Computer hardware enthusiasts have literally waited for years for AMD's Bulldozer architecture to come to market and we finally see this today in its desktop form, code named Zambezi, brand named AMD FX. In this article we share with you our analysis of Bulldozer's performance in synthetic benchmarks and desktop applications.

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Overclocking

First and foremost I did all of my overclocking of Bulldozer on the ASUS Crosshair V Formula motherboard. This is a $229 motherboard at Newegg, and if that is in your budget you are stupid not to pick this one up for Bulldozer action. The board has every bell and whistle you will want.

I ran all of the previous benchmarks at 4.6GHz on the FX-8150 and FX-8120 processors. I got the processors in, started testing, found what I thought was stable and easy to reach using our Corsair H100 cooler and then got to running the somewhere around 250 individual tests that we do for a story like this. When I got done with all that benchmarking, I turned back to overclocking the FX-8150 and FX-8120. What I found out then was that holding a successful 4.6GHz overclock at full load was not practical with the cooling that we were using. And the Corsair H100 is no slouch when it comes to cooling, it is in fact a stout unit. The ambient temperature in my office ran about 86F/26C all week with the test systems running constantly. I figure 26C is good median temperature for what you might find across North America, this summer withstanding. Let me point out that when I say "successful 4.6GHz overclock at full load" I mean absolutely 100% stable under 100% CPU and 100% RAM load for at least a 12 hour period. Unless you are Bitcoin mining or Folding, you could likely use this system at 4.6GHz as we tested without issue.

My 8120 pulled 1.32vCore at stock settings when scaling up to the 4GHz Turbo mark. At idle my 8120 pulled 0.948vCore. Overclocking the 8120 to 4.7GHz and getting good stability required only 1.5vCore. The core was running about 66C. However after being loaded for 10 minutes or so, we would have one core fall off to zero utilization. You would not get a crash, or any errors, you just simply lost 1/8th of your processing power. Pushing the vCore beyond 1.51v or so, I would have BSOD issues trying to push for 100% full load stability. The ASUS Crosshair V motherboard has a LOT of power features and while I did use all of these, I certainly did not try all combinations of these. I am still looking for an "APM" setting in the BIOS. (And yes I did ask.) This particular APM setting is described by AMD as, "disable APM_Master_En (disables APM which may cause the CPU to throttle at full load)." I never could find this switch that actually kept cores from dropping off under load. Another problem with going past the 1.5vCore limit is that you will bump into the current limit allowed. Again, here is what AMD had to say, "try CPU voltage values between 1.40آ…1.55V and find the optimal setting آ– if the board just shuts down during full load it means it hit OCP limit (this seems to happen once the CPU pulls more than 26.5A from the 12V CPU rails (8pin and 4pin connectors). You’ve hit the OCP limit and should decrease the voltage a bit." This results in the system just simply turning off. Thank goodness Windows 7 is lenient about this shutdown issue, and thank goodness the Crosshair V has no issues POSTing after a failed OC attempt. I used both of these "features" many times in the last week.

Overclocking the Bulldozer was actually the most fun I have had OCing in a long time. If you are the guy that likes to get in there and tweak for hours, the Crosshair V and Bulldozer are right up your alley. I could easily spend another week under the hood with Bulldozer finding the hairy edge.

That all said, with our FX-8120 I had to settle for a 4.5GHz OC at 1.52vCore and that even ended up dropping a core on me overnight. Hopefully I'm just missing the APM switch that AMD notes above (and I hope that might "fix" my core drop-off issue) but everything labeled APM or other power functions in the BIOS did not seem to have effect. Hopefully I will get a solid answer from ASUS or AMD on this.

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Now if you plunk down the extra hundred bucks on the 8150, here is what you are buying, or at least what I saw with my 8150, your mileage may vary. The 8150 silicon is simply a little bit "better." A very stable 4.5GHz OC at 1.44vCore. I did however have the same problems at 4.6GHz no matter how high I took the vCore, same as the 8120.

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Also we found what we think is a bug and made AMD aware of this, and I think this might impact some of the benchmarks you see today around the Web. When using AMD OverDrive to overclock the Bulldozer processors from the Windows 7 desktop, we found that if you turned off Turbo Core in the application, then clocked the processor up through AOD, it would negatively impact the memory bandwidth by about 25%. So once we found this issue and verified what was happening, we did all of our overclocking through the robust ASUS Crosshair V BIOS.


Conclusions

AMD has finally delivered what it has promised for years, Bulldozer. It was four long years ago that we first talked to you about Bulldozer. What AMD brought to market, and what it talked about four years ago are two very different things. There is no denying that somewhere in the last four years the train fully left the tracks. I can't lie, I have thought more than once while going through all the data that AMD might have been better off concentrating on a successful die shrink and clock scaling of its current flagship desktop processors rather than spending the money on Bulldozer development.

So what has AMD delivered to the desktop in the form of Bulldozer?

AMD has delivered what will be a disappointment to many. The Intel fanboys have won this round. There just isn't any way around it. AMD fans, get ready to eat crow. If you expected something to outshine Sandy Bridge in terms of performance overall, it is just not there. frown

Bulldozer has surely been built with the future of computing in mind. And seemingly a lack of backward vision whatsoever. In single threaded applications Bulldozer gets its ass handed to it by Intel's Sandy Bridge Core i5 and i7 K series processors. Conversely, the moments where we see Bulldozer shine it is deeply computing through multithreaded applications, but even then it is not shining that brightly. Still Bulldozer's sum is greater than its parts as the metrics have shown.

You synthetic benchmark monkeys will not be swinging from Bulldozer branches either as that is a disaster.

When you look at how much power the enthusiast's overclocked Bulldozer system will chew through under those multithreaded workloads, you have to realize just how much wattage you are giving up to not have an Intel processor. (Yes, we know some of you are brand loyalists.)

There is a silver lining to this. AMD's unlocked FX-8120 is to be priced at around $200 in retail. You noticed we did not spend a lot of time pontificating about the FX-8150? The reason is because, from an enthusiast standpoint, there is simply no reason to buy an 8150. The 8120 and the 8150 are the same silicon. Yes, AMD is doing some silicon culling looking for which ones will take less vCore to hit the 4.2GHz Turbo specifications, and of course those parts are going to get the 8150 badge. For $200 you can purchase an AMD FX 8 core processor that will overclock to the mid-4GHz speeds fairly easily.

Is there any burning reason as to why you should buy AMD's $200 chip rather than Intel's $200 chip? I really can't give you one. The Bulldozer is harder to overclock for the most part and surely more picky about its voltages than Intel's Sandy Bridge. Bulldozer is going to take a heavier cooling solution than Sandy Bridge.

From an enthusiast performance standpoint, the FX-8150 is wedged in between the 2500K and 2600K parts in deeply threaded workloads, with it being closer to the 2500K for sure. In single threaded applications Bulldozer is coming in behind even our Phenom II X6 1100T. Of course we are seeing much higher clock speeds from the Bulldozer than the older AMD Thuban core.

The FX-8120 performance is solid and I had no issues whatsoever working with the new Bulldozer systems. The desktop felt as fluid as it ever has with any of my HyperThreading processors. The only place I could find a discernible difference during desktop usage was when I had my systems loaded 100% CPU and 100% RAM. The AMD system became somewhat unresponsive, while Intel's will still let me get my clicks in to make things happen.


Bulldozer and Gaming

We broke Bulldozer gaming out into an article of its own and used all real world gameplay. We actually ended up with some surprising results. You will want to read that as well. Most folks will still find themselves GPU limited, but we were able to find at least one example of being CPU limited for sure.


The Bottom Line

What we wanted out of Bulldozer and AMD and what we are getting are two different things. AMD has built a very good processor in Bulldozer that can be had at a very good price. Bulldozer however is just some "Me too!" when comparing to Intel's $200 2500K Sandy Bridge part that has already been out for a good while.

Single threaded Bulldozer performance leaves a lot to be desired. Bulldozer is truly in its element when it can flex all its cores on the workload at hand. And this of course is the where software is moving to.

While there is not much of a compelling reason to buy an FX-8120 and overclock the snot out of it, there is also no real compelling reason to not buy an FX-8120 either. Yeah, the power consumption is a bit ugly, but 200 watts is not the end of the world. An enthusiast with a decent 990FX chipset motherboard and $100 worth of cooling should be able to take the FX-8120 to the mid-4GHz mark without much trouble. And from what I can tell, you are likely going to be happy with it.

Would I put an AMD FX in a system I might be building? I can say, "Yes I would, as long as it is not for a geek." But if you asked me if I will be putting an AMD FX in my next personal system I would probably have to tell you, "No." If I had to build a system for myself tonight, it would have a Intel Core i7-2600K in it. I can't point to the AMD FX-8150 or FX-8120 being a bad choice, but I just do not think either of those is the best choice.

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