The Phenom II X6 - AMD Replies with Six Cores

Introducing the AMD Phenom II X6

Ladies and gentlemen, the multi-core race on the desktop front has now officially moved into 6-core territory. Intel grabbed the headlines with its first 6-core desktop processor last month, the , but let's not forget that the first 6-core x86-class processor in the market was the AMD "Istanbul" Opteron. AMD has now brought this server/workstation series to the desktop and intends to launch a series of processors using this 6-core architecture, nicknamed "Thuban" and collectively known as the Phenom II X6. 

Based on the same Phenom II architecture that underpins its current quad-core lineup, Thuban promises six cores on a single die, and is manufactured using GlobalFoundries' 45nm SOI fabrication process. AMD has managed to keep the thermal envelope similar to its quad-cores at 125W TDP for the two models launching today despite the increase in core count, thanks to GlobalFoundries' use of low-k dielectrics materials. Looking at its 2010 roadmap, one can expect even lower, 95W variants by the middle of the year. All of them are compatible with existing AM2+ and AM3 motherboards after a BIOS update, which should be good news for those looking to upgrade their AMD systems.

The core specs should be familiar to anyone who has kept up with AMD's architecture. The company may tout it as a true 6-core solution and there are indeed six distinct processor cores, but the amount of L3 cache on the AMD Phenom II X6 is identical to that on the quad-core  Phenom II. Other staples of the architecture, like the HyperTransport bus and integrated memory controller remain the same as on the quad-cores. The L2 cache has grown proportionally to the number of cores, with 512KB for each. The frequency of the top model, the unlocked, Black Edition AMD Phenom II X6 1090T starts at 3.2GHz while the other, the X6 1055T clocks at 2.8GHz. Below are the specs and pricing details for these new Phenom II X6 processors. 

A Matter of Turbo

You probably have noticed the 'T' in the model numbers and the 'Turbo Core' frequencies listed above. This is AMD's new feature for its Thuban architecture processors - Turbo Core. Feeling a pang of deja vu about this term? You aren't too far off the mark if you're guessing this is related to Intel's Turbo Boost. Turbo Core is AMD's take on which if you can remember, is a feature that dynamically scaled up the processor's clock speeds (by a varying number of speed bins) when the application load on the processor is lightly threaded. Idle cores are almost switched off completely and consume close to zero power while the remaining, active cores are bumped up. There is a limit on the total amount of 'overclock' you get from Turbo Boost, which is set by the thermal envelope of the processor.

AMD's version is quite different. For Turbo Core, when three or more of the six cores are idle, the processor's clock speed for the active three cores go up to 3.6GHz for the Phenom II X6 1090T. This is a 400MHz boost for lightly threaded applications. However, unlike the granularity of Intel's technology, which has a varied amount of clock boost according to the number of cores in use (one could get a small increase in clocks for all four cores if the TDP is not exceeded for example), AMD's solution is binary in nature.

So, three cores on the 1090T get boosted to 3.6GHz while the remaining three drop down to its idle state, which is 800MHz on the 1090T along with a corresponding drop in voltage. This move allows AMD to keep the processor within its thermal envelope and which AMD says is a benefit - unlike Intel's Turbo Boost, which depends on keeping within the thermal envelope to improve the extent of the clock increase and is hence partially dependent on your cooling system - AMD's Turbo Core gives a fixed amount based on load and is not dependent on temperature. It also means that AMD's Cool'N'Quiet must be enabled for it to work as intended. 

More importantly for consumers, Turbo Core works in the background (enabled or disabled in the BIOS) and does not depend on software drivers or the OS. It's done completely through the hardware and the usage/load will trigger Turbo Core when it meets its criteria. Finally, Turbo Core will not be restricted to just the 6-core processors. AMD plans to have them on upcoming 'Thuban' quad-cores (essentially 6-cores with two cores disabled), which would have the 'T' designation in its model name as the distinction. Presumably, one would see a 2/4-core Turbo Core split then.

The AMD 890FX Chipset

With the new processor's backward compatibility with existing chipsets, there's no need to run out to get a new motherboard for the AMD Phenom II X6. But in case you're feeling the upgrade itch, AMD has a whole slew of updated chipsets to meet your needs, from the mainstream 880G (an updated 785G) to the 890GX that was released last month. For the enthusiast segment, AMD has updated its 790FX chipset and renamed it 890FX. These motherboards will be available around the same time as the Phenom II X6 and should be a fitting companion for the enthusiast, what with its support for up to quad-CrossFireX and SATA 6Gbps.

Like the , the major new feature on the AMD 890FX is the presence of the new SB850 Southbridge. SATA 6Gbps is native on this Southbridge, though USB 3.0, while supported on many newer boards, is still implemented via a third-party NEC controller. There is however 14 USB 2.0 ports, with the usual HD audio and Gigabit Ethernet rounding off the Southbridge.

There's no integrated graphics on the 890FX of course, but bandwidth is not an issue, with up to four x8 PCIe lanes for quad-CrossFireX should the motherboard vendor decide to go with this configuration. The alternative is the more common two x16 configuration. The 890FX also has hardware support for IOMMU, which is a feature not found on the lower tier 890GX. This is something for those who use virtualization, as the feature enables system devices to use their native drivers in a virtualized environment, leading to better performance. It's not a feature you'll see on desktop chipsets, and according to AMD, even those who are not into virtualization, can benefit from having a dedicated hardware controller doing memory isolation and protection.

AMD OverDrive and Fusion Desktop Utility

AMD also has updated its utilities for the launch. OverDrive (ver 3.2.1), its tweaking and monitoring tool, gets a refresh, notably with the addition of Turbo Core Control for users. This allows users to check if Turbo Core is working properly and to what extent, along with a clock and voltage tuning section. The new chipsets, 890FX and 880G are also supported on the new version. Together with the usual tweaks and overclocking adjustments, it should keep any enthusiast occupied. 

Meanwhile, AMD's Fusion Utility for Desktop is into its second version. It's targeted at more casual users that ideally have both AMD CPU and GPU in their systems. There are tools for performance tuning of both the graphics and the processor for the enthusiast, while preset profiles and Auto-Tuning options are available for the less experienced. It supports Windows Vista and 7 only.

Test Setup

AMD recognizes that even with six cores, its Phenom II X6 processors will find Intel's more expensive offerings out of their performance and price bracket. Hence, the ideal price-competitive rivals for the Phenom II X6 1090T are the Core i7-930 and Core i7-860, which at US$295 and US$280 respectively, are closest to the US$289 retail price of the 1090T. Meanwhile, the US$199 Phenom II X6 1055T is pitted against Intel's mainstream Core i5-750, which is being sold at that price. For comparison's sake, we have also included results for AMD's current quad-core champ, the Phenom II X4 965 (US$186) and also Intel's 6-core Core i7-980X.

To find out the effects of Turbo Core on performance, we have also ran our benchmarks for the 1090T with and without Turbo Core enabled. While we believe that one should have Turbo Core enabled all the time, it would be interesting to find out how the 6-core fares without this new feature. Below are our test configurations and benchmarks.

AMD Phenom II X4/X6 Test Configuration

• ASUS Crosshair IV Formula (AMD 890FX + SB850, 0602 BIOS) for Phenom II X6 1090T (3.2GHz), 1055T (2.8GHz)
• MSI 790FX-GD70 (AMD 790FX + SB750) for Phenom II X4 965 (3.4GHz)
• 2 x 1GB Kingston HyperX DDR3-1333 (7-7-7-20)
• Zotac GeForce GTX 260 (ForceWare 178.24)
• Seagate Barracuda 7200.10 200GB SATA hard drive (one single NTFS partition)
• Microsoft Windows XP Professional with Service Pack 2

Intel Core i7 Test Configuration

• Intel Core i7-930
• Gigabyte X58 Extreme (Intel X58 Express chipset) (F11 BIOS)
• 3 x 1GB Kingston HyperX DDR3-1333 (CAS 7-7-7-20)
• Zotac GeForce GTX 260 (ForceWare 178.24)
• Seagate 7200.10 200GB SATA hard drive (one single NTFS partition)
• Intel INF 9.1.0.1007 and Matrix Storage Manager 8.6.0.1007
• Microsoft Windows XP Professional with Service Pack 2

Intel Core i5/i7 (Lynnfield) Test Configuration

• Intel Core i5-570, Core i7-860
• Intel DP55KG (Intel P55 Express chipset)
• 2 x 1GB Kingston HyperX DDR3-1333 (CAS 7-7-7-20)
• Zotac GeForce GTX 260 (ForceWare 178.24)
• Seagate 7200.10 200GB SATA hard drive (one single NTFS partition)
• Intel INF 9.1.1.1015 and Matrix Storage Manager 8.9.0.1023
• Microsoft Windows XP Professional with Service Pack 2

Benchmarks

The following benchmarks were used in this review:

• SPECCPU 2000 v1.3
• BAPCo SYSmark 2007 Preview (ver 1.05)
• Futuremark PCMark 2005 Pro
• Lightwave 3D 7.5
• Cinebench 10
• Futuremark 3DMark06 v1.1
• AquaMark3
• World in Conflict v1.05
• Crysis v1.1

Results - SPECCPU 2000 v1.3

While the Intel contingent predictably had higher peak values for both integer and floating point performance in this benchmark, the focus was on how the Phenom II X6 performed relative to the quad-core Phenom II X4 965. The X6 1090T however failed to show a significant improvement over the 965 for both. Moving onto the integer rate results, the 1090T managed to stay competitive with the Intel Core i7-930, but not in floating-point rate results. However, the AMD 6-cores both showed improvement over the Phenom II X4 965 at 8-user workloads, which does prove that there is some value in having more cores if you have highly threaded workloads.

Results - SYSmark 2007 Preview

Interestingly, in SYSmark 2007, we found that enabling Turbo Core appeared to have little effect on the overall score. However, given that the margin between the 1090T and the 1055T is so narrow, it could be that with or without Turbo Core is just too close to call. We do find some differences in the breakdown, with the Turbo Core improving the Productivity and 3D scores, though having no Turbo appeared to benefit Video Creation, which on paper, should have negligible difference, since we can assume that video encoding would stress all the cores and hence Turbo Core should have no impact.

In any case, the two Phenom II X6 processors fared decently against their intended rivals. The 1090T was slightly faster than the Core i7-930, but lost out to the higher clocked Core i7-860. The 1055T lost out (though not by a lot) to its Intel competitor, the Core i5-750, which again, when running with Turbo Boost, has higher clocks than the Phenom II, not to mention that Intel has managed more instructions per second with its architecture. 

Results - Futuremark PCMark05 Pro

Going by PCmark05's CPU score, the Phenom II X6 was on par with AMD's own expectations, with the 1090T beating the Phenom II X4 965, the Core i7-930 and i7-860. The 1055T was less impressive, though it too managed to stay competitive with the Core i5-750. When it comes to the memory subsection however, the Phenom II architecture was as usual, trounced by the Intel processors; the only consolation is that the Phenom II X6 did beat its own quad-core competitor.

Results - Lightwave 3D 7.5

One of the main reasons for buying a processor with more cores - 3D rendering. And Lightwave 3D should help to illustrate this. With the Tracer-Radiosity workload, the 1090T was second only to the Core i7-980X, with Turbo Core making a significant impact. The performance of the 1090T without Turbo Core was slower than the Phenom II X4 965, but this changed once we enabled it. Meanwhile, the 1055T was faster than all of the Intel processors except for the Core i7-980X at four and eight threads. The Intel contingent did improve in the Sunset workload, which eroded AMD's slight lead and made it very competitive between the two camps. 

Results - Cinebench 10

Another rendering benchmark to show off the best of the multi-cores, we weren't surprised to find the Phenom II X6 1090T taking second spot behind Intel's own 6-core juggernaut, which was in a class of its own. Turbo Core did not matter here, as all the cores are fully taxed, which meant that there was no boost. Against its Intel rivals, the two Phenom II X6 processors definitely had the edge.

Results - Futuremark 3DMark06 & AquaMark3

The Phenom II X6 continued its decent run in 3DMark06, where they were competitive in both the CPU score and the overall. Turbo Core here played its part in ensuring that the 1090T was just ahead of the Core i7-860. AquaMark3 however saw the Intel camp streaking ahead and even the Phenom II X4 965 had marginally higher CPU scores than the 1090T.

Results - World in Conflict & Crysis

It's in the gaming benchmarks that we ran into some hitches. World in Conflict had the Phenom II X6 barely matching the Phenom II X4 965, which at 3.4GHz, is admittedly faster than the default (non Turbo) 1090T. However, that just meant that Turbo Core was not really helping in this benchmark, despite our impression that this game could not be using three cores. More bad news was to follow in Crysis. Discounting the Intel processors, the Phenom II X6 was surprisingly a lot slower than the Phenom II X4 965. It was such a shock that we even reformatted our system and reinstalled everything to verify that everything was in order - twice!.

However, the scores did not improve with the format and the Phenom II X6 was still much slower than the Phenom II X4 965. We decided to try it in Windows 7, where presumably there should be no issues related to the OS scheduler and its effect on Turbo Core. While the scores were much improved (more likely due to the newer 195.62 ForceWare drivers for this newer OS), they were still a long way off what we expected. Trying the 1090T with another motherboard (the MSI 790FX-GD70) yielded similarly poor results, which led us to conclude that this issue was with the processor. Meanwhile, we'll keep a tab on this to investigate this outcome further in the near future.

Power Consumption

AMD has done a decent job of keeping its power consumption within the limits and at idle, the Phenom II X6 consumes a similar amount of power to its top quad-core. In fact, it even gives Intel's equivalent 6-core a run for its money, which should be some sort of achievement considering that Intel is on a 32nm manufacturing process. While this trend continues as we loaded the processor, it's apparent that the Phenom II X6 cannot compete with its stated targets - the Lynnfield processors - when it comes to power draw. Turning off Turbo Core nets you minimal benefits in terms of power consumption, and applicable only to lightly threaded applications, like 3DMark06. 

Overclocking

Next, overclocking was relatively hassle-free thanks to the tools available. Not only does AMD OverDrive allow users to tweak their clocks and voltages, our ASUS Crosshair IV Formula board's BIOS allow us to specify the amount of Turbo Core boost. Our final attempt landed us close to 4GHz, with the processor passing our stability test only at 3.9GHz, with a Turbo Core of 4.2GHz. 

Overclocked at 3.9GHz with 4.2GHz Turbo, the Phenom II X6 was roughly 16% faster than the default. Of course, this will vary from application due to the nature of Turbo Core, but it should be a decent amount, especially when we were just trying this air-cooled.

Conclusion

One can't help but have mixed feelings about the Phenom II X6. AMD has to get some credit for bringing a 6-core processor down to less than US$300 for the top, unlocked model, which is pretty affordable, considering that this sum just about gets you an above average Core i7 quad-core. Throw in the new Turbo Core feature that seeks to alleviate the weakness of multi-core processors - in order to keep within the TDP, they are generally restricted to lower clock frequencies than dual-cores - and we should have a winner right? That's even before one considers that at 125W TDP, these Phenom II X6 processors are quite close to the quad-core Phenom II X4 965 in terms of power consumption.

The fly in the ointment is that all those extra cores only get to show off their capabilities in certain applications, namely those CPU intensive, multi-threaded ones, like video encoding and 3D rendering. While Turbo Core helps to a certain extent to improve lightly threaded performance, it's not as powerful or as flexible as its inspiration, Intel's Turbo Boost and its power-gating scheme that reduces the voltage of idle cores to almost zero.

In the end, what you make of the Phenom II X6 boils down to your usage. If one judges an all-round system suite like SYSmark as the gauge, then there's hardly any difference between Turbo Core or not. For those who are heavily into multi-threaded applications, then the results, exemplified by Cinebench, will be a distinct improvement over AMD's own quad-core.

However, if gaming is your focus, then the Phenom II X6, despite Turbo Core, is as lackluster as any of AMD's processors. When everything works fine, like in World in Conflict or a gaming benchmark like 3DMark06, one gets negligible to marginal improvements. If it's like our experience in Crysis, then something's obviously not working properly and even a high-end graphics card, like AMD's own Radeon 5800 series, will be constrained by the processor. Intel's Lynnfield processors will be the better deal here, especially coupled with their very decent overclocking limits and vastly lower power consumption.

There's no doubt that the Phenom II X6 1090T is very affordable for a 6-core processor at US$289, but while it manages to just edge out its opponents, the Core i7-860 and i7-930 in some multi-threaded applications, it's in turn heavily beaten by them in lightly threaded ones. It should nevertheless pull some users away from Intel, especially for certain usage models. In fact, the X6's greatest competitor may come from within. The quad-core Phenom II X4 965 is around US$100 cheaper at $186 and it's generally not that far off from the Phenom II X6 1090T. Is that premium worth paying for two more cores? Check your own list of applications to find the answer. 

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