Review: AMD FX-8150

AMD FX-8150 - Overview

We've waited a long time for AMD to release a brand new processor architecture, but finally the AMD FX-8150 has arrived.

This first chip is the vanguard of the somewhat tardy Bulldozer technology and is this top-of-the-line AMD FX chip, code-named Zambezi. This is the full-fat, eight-core AMD super-chip running at a not inconsiderable 3.6GHz straight out the box.

The FX moniker isn't a new one for AMD chips.

The last time we saw it used for its high-end parts was in the 90nm Athlon 64 FX-74 in late 2006. It's been reborn this year to cover the first in what AMD hopes will be a long line of Bulldozer-based CPUs.

The AMD FX CPUs represent the chip maker's first real new architecture since the exciting times of the first Athlon back in 2003.

And it is very much a new architecture; AMD has started from scratch with the design of the Bulldozer modules, taking a very different approach to what makes up a CPU core than anyone else.

We'll explore the depths of that architectural change later, but the real key is the use of that word 'module'.

Each of these modules holds the essential makeup of a standard dual-core processor, sharing certain non-timing sensitive parts.

The AMD FX-8150 has four of these Bulldozer modules and AMD claims that makes it the world's first eight-core desktop chip. It's tough to ignore the sickly sweet scent of fudge here, though this hardware-based solution ought be a lot more effective than Intel's mostly software-oriented HyperThreading.

The Bulldozer module represents the future of AMD processors going forward.

Speaking with Bernard Seite, an AMD Technical Advisor, last month he told us that the Bulldozer modules are likely to last as the basis for its CPU range for the next 5-7 years.

At the moment we've only seen the roadmap for the next couple of years, with the Piledriver update coming next year, Steamroller coming in 2013 and Excavator in 2014.

Yes, we know it sounds like a joke, but AMD's latest roadmap really does read like the Urban Dictionary Karma Sutra.

But hopes are still high for these new AMD FX processors, especially after it managed to snag the Guiness World Record for highest CPU clockspeed in September.

We saw this top CPU here running at well over 8GHz.

That is impressive, but realistically it's just numbers. The world record didn't demand the machine to actually run any applications, it just needed to boot into Windows and report it's clockspeed. It also didn't need to be running all its cores. The world record was actually only broken by a single Bulldozer module in operation and under serious liquid helium cooling too.

The precedent is there though and means the AMD FX-8150 ought to be one hell of an overclocker's chip. What that will mean in real-world applications though we'll soon see.

So how does the new AMD FX CPU stack up then? Can it give Intel's Sandy Bridge a run for its money and can it make AMD a performance chip manufacturer once more?

AMD FX-8150 - Architecture

The AMD FX-8150's new Bulldozer technology is a fairly radical departure from the standard model of processor design.

The big news is the modular design housing the constituent components of a dual-core CPU in one.

It's also AMD's first 32nm desktop CPU. Sadly that does make the chip seem a little behind the times with Intel set to release it's first 22nm processor in Spring next year.

But like Intel's shift in process size the change to this modular design allows the AMD engineers to squeeze more performance into a smaller space, and therefore also cut the costs of manufacturing.

Essentially the idea is to share parts of the module with lower utilisation, such as the Level 2 cache, Fetch and Decode components, while high utilisation parts, such as the Integer pipelines and Level 1 data cache, are separated out per core.

According to AMD that should give each Bulldozer module around 80% of the performance of a standard dual-core CPU.

It's this squeezing of two cores into each module that means AMD can produce an eight-core CPU for less than the price of Intel's top Sandy Bridge quad-core.

And seeing as competition on price rather than performance is more of AMD's concern than Intel's that's something it had to do with the AMD FX CPUs.

Still, like the AMD FX-8150 the Core i7 2600K - that top Sandy Bridge chip - can run eight processes in parallel.

Intel doesn't call it an eight-core chip, instead uses its HyperThreading technology to split the four cores in its die into eight processes. There is a certain amount of hardware in the Sandy Bridge die to make the HyperThreading magic happen, but mostly it's a software-oriented model.

Intel's way of spreading out four cores into eight processing threads operates mainly by effectively managing instructions going into one core and separating that out into two parallel threads for the operating system.

Turbo

Again like the Intel chips, the AMD FX CPUs use a form of on-the-fly overclocking to boost performance when there's spare capacity available.

The AMD Turbo Core technology has been used in the Phenom II CPUs before, but has been specifically enhanced for the Bulldozer architecture. Now it can use the Turbo Core to offer increased performance when all cores are active should the TDP headroom exist for it to do so.

The AMD FX-8150 has a standard clockspeed of 3.6GHz, with a possible Turbo Core available to it to allow it push up to around 3.9GHz.

When only a single core is needed though then Max Turbo comes into play.

This essentially takes the available TDP headroom for the entire chip and focuses it onto a single core giving it the ability to push even further in terms of clockspeed.

On the AMD FX-8150 that means it's theoretically possible for the chip to hit 4.2GHz as standard when only one thread is needed.

But what about the platform?

Despite the delay to the actual CPUs themselves the motherboard platform was actually launched a fair while back. The AMD 9-series motherboards have been doing a roaring trade out there even without the chip to back them up.

There's precious little difference between the 8-series and 9-series motherboards save for one vital ingredient; the AM3+ socket that supports the new AMD FX CPUs. That also means they aren't the priciest boards in existence.

Still, to get the best out of your Bully CPU, at least in overclocking terms, then dropping some cash on a decent board should be well worth the money.

To this end AMD is shipping out the Asus RoG Crosshair V Formula with each review kit.

That's a brief overview of the technologies behind AMD's latest chip architecture, and mighty impressive it looks on paper. But how does it perform in the real-world? Overclocking records aside, what will happen when you drop this chip into your motherboard at home?

Let's take a look.

AMD FX-8150 - Benchmarks

The first benchmark below is possibly one of the most telling.

Taking the eight-cores of multi-threading out of the picture you can see how the individual cores actually stack up. Running in single-threaded mode shows the FX-8150 cores actually running slower than the hexcore Phenom II it's replacing.

With the multi-threaded benchmarks though the FX-8150 starts to look more interesting. However the gaming benchmarks tell a worrying story.

When it's just relying on the GPU the story is much the same across the four CPUs we tested. DiRT 3 is shown here, but in Just Cause 2 and World in Conflict all four processors spat out roughly the same performance figures at the top resolutions.

Take the GPU out of the equation and the Sandy Bridge chips stretch out ahead.

Things aren't too pretty in terms of multi-GPU performance either.

In overclocking terms though the FX-8150 is a success. Stably running at over 4.7GHz is impressive and really pushes it ahead of the Core i5 2500K.

If the chip had been released at the 4GHz it can easily manage we might've been looking at a higher score...

Single-threaded performance

Multi-threaded performance

CPU gaming performance

High-end gaming performance

Multi-GPU performance

Overclocking performance

Platform power draw

AMD FX-8150 - Performance

All the clever architectural tricks in the world count for nought if the performance isn't there, so how does the top-end AMD FX chip stack up against it's rivals?

The short answer is not as well as we might have hoped.

AMD really needed this chip to be at least a rival for the current generation of Sandy Bridge CPUs, especially with a new production process and accompanying chips arriving in the first half of next year for Intel.

With the high clockspeed and nominal eight cores, we had hoped to see the AMD FX-8150 taking the resolutely quad-core Intel Core i5 2500K to task.

Indeed with that chip artificially hobbled by the switching off of HyperThreading you'd think it wouldn't be much of a contest.

In fact it's a lot closer than Intel could have dared hope, and certainly a lot closer than AMD would have wanted. Especially in the multi-threaded benchmarks, and that's quite a surprise.

In the heavily multi-threaded Cinebench R11 test the AMD FX-8150 comes away with a decent 5.98 index score, but with only four threads of processing grunt against the FX chip's eight the i5 2500K manages to get awfully close at 5.90.

That test is also interesting when you compare the previous top AMD chip, the Phenom II X6 1100T.

That's a full six-core CPU, but is running on the older 45nm hardware and at a slower clockspeed too. Yet that older brother still manages to put up a score of 5.88.

The eight-threaded Core i7 2600K however is streets ahead of all three.

Still, those extra threads come into account with the X264 video encoding benchmark. Even at stock speeds the FX-8150 actually starts clawing back some ground on the i7 2600K, beating the quad-core i5 2500K easily as it does.

Unfortunately the actual cores in the Bulldozer modules look like the weak link in the multi-threaded chain.

A quick check on the single-threaded performance of the FX-8150 highlights that weakness.

Using the single-threaded Cinebench R10 benchmark you can immediately see the problems the FX-8150 faces. Even the ageing Phenom II cores run faster than this brand new Bulldozer core.

And the two Sandy Bridge chips demonstrate just what an advantage their cores have over the AMD processors.

Gaming

The gaming benchmarks are similarly telling.

On the whole at the high end of the graphics spectrum, at the high resolutions, it's all about the graphics hardware. As long as the chip's not getting in the way then the GPU can operate with impunity.

Take the GPU out of the equation however and things get more interesting.

World in Conflict is a great CPU benchmark in gaming terms as different CPU hardware genuinely can show a difference. We ran the benchmark at the lowest resolution and lowest graphical fidelity, while retaining CPU-heavy operations such as physics, just to make sure the CPU was taking the load.

The two AMD CPUs behaved much the same, while the Sandy Bridge chips were well over a third faster.

We were hoping to run the Shogun 2 CPU benchmark too in order to see how things stood on a more modern engine. Sadly the game refused to load for the Bulldozer chip...

The AMD FX-8150 though is meant to be a rather capable gaming chip, and with a high-end GPU it delivers performance every bit as good as the Intel chips.

So there's nothing holding it back in gaming terms.

What about multi-GPU though? The FX-8150 ought to be a better bet for dual-graphics setups thanks to the two native x16 PCIe lanes within the platform.

And if you just took DiRT 3 as the only gaming benchmark worth a damn then all would indeed be rosy.

Using the AMD-sponsored title it garners an extra 3FPS over the competing Core i5 2500K. Not an impressive lead, but a lead nonetheless.

In the DX10 World in Conflict and Just Cause 2 benchmarks though the FX chip lags behind, in the case of WiC by over 25FPS.

There's no problems with the GPUs, or how they're talking to each other, as the GPU-centric Heaven 2.5 test ignores all the other hardware and just gives a score based on what the GPU is capable of. In both AMD and Intel setups the Heaven score was identical.

AMD will argue that legacy software is not where you'll see the benefits of the new hardware.

It may have a case, but still the vast majority of games released today are not DX11 games, they're DX10 and in some cases DX9.

The OC

But there is at least some good news for AMD though, and that is all down to the fact it has finally created an overclocking-friendly processor.

We've been used to 1GHz+ overclocks from Intel chips for a while now, and with the AMD FX-8150 we've managed to get the same scale of improvements.

With a Corsair H100 water-cooling block we were able to push the FX-8150 to an impressive 4.73GHz. With the same cooler we could only get 4.6GHz out of the two Sandy Bridge chips.

When you're pumping out that sort of performance then the benchmarks start to look a lot more impressive.

Now with the CPUs at their maximum overclock the Cinebench R11 test shows the FX CPU easily outstripping both the Phenom II X6 1100T and the Core i5 2500K.

The i7 still remains way out in front, though in the X264 test only by a single frame per second on average.

AMD FX-8150 - Verdict

Inevitably the performance of these chips is where they are going to be judged in real terms.

And somewhat inevitably it's something of a disappointment.

It's somewhat inevitable as AMD simply doesn't have the vast research budget of its Silicon Valley rival, Intel. We don't want to start making excuses for AMD though, and the FX-8150 is by no means a bad chip.

It is definitely the fastest CPU AMD has on the market right now.

Take Intel out of the equation and we'd be lauding the Bulldozer architecture as a truly remarkable thing.

The problem is Intel is most definitely in this equation and we've had this sort of performance, for around this sort of price, since we first clapped benchmarks on Sandy Bridge.

But Bulldozer remains the future for AMD.

And there is genuine hope on the horizon. The Trinity APU for example will be running the enhanced Piledriver architecture alongside discrete-class graphics in the same die.

For now though the top-end, eight-core AMD FX CPU struggles to keep pace with Intel's middling, ageing, cheaper and resolutely quad-core, Sandy Bridge i5 2500K.

And that's the big problem.

The FX CPUs are almost competitive with their Sandy Bridge rivals, but still can't beat them.

The 2500K is a cheaper chip and represents a better bet for gamers. If you want multi-threaded prowess too then for only another £50, at worst, over the FX-8150 you can pick up the awesome i7 2600K.

This is though only one of the Bulldozer-based chips AMD has launched, and the lower-end CPUs may actually be far more worthy.

The 3.1GHz FX-8120, for example, is available for around £165 – less than the 2500K – and should still have the overclocking chops thanks to the unlocked nature of the entire FX range.

Topping 4GHz with that CPU could turn it into a really very good gamer's chip with added multi-threaded extras to boot.

Still there is more to come from Intel, with another LGA 1155 Sandy Bridge reportedly on its way and the brand new, ultra high-end Sandy Bridge E is soon to touch down too.

We liked

The modular architecture is impressive and ought to pay off for AMD further down the line.

As it is the FX-8150 is an impressive overclocker's chip. Hitting 4.7GHz gives the chip one hell of a boost in performance terms.

We disliked

Unfortunately the chip's just not competitive enough against its rivals.

At stock speeds it struggles against the non-HyperThreaded i5, even in some multi-threaded applications. And while it keeps pace with the competition in gaming terms it loses it when you come to adding in extra GPUs.

Even AMD ones.

Final word

We can't help but feel disappointed with the lack of performance progress the FX-8150 represents. It's not a bad chip, but we wanted more.