AMD A8-3850 Fusion APU £100
30th Jun 2011 | 04:02
AMD's first performance Fusion APU
AMD A8-3850 Fusion APU: Overview
The AMD A8-3850 Fusion APU is the current top-end desktop Llano chip, and is a bit of a doozy.
Last month saw the launch of the first Llano Fusion chips from AMD on the notebook side, the AMD A8-3500M, and if that isn't enough alliteration for you we've now got the release of the desktop Llano APU code-named Lynx.
Before we go any further we ought to get into what the hell we're talking about when we're going on about an APU.
It's an Accelerated Processing Unit, essentially that means it's a combo chip combining both traditional CPU and GPU parts in one die. That's right, we're back to the old days of the one chip to rule them all, though this time we've actually got graphical prowess to shout about.
AMD has released Fusion APUs before now, with its lower-end Brazos chips (Zacate and Ontario) paving the way for this far more serious, performance part. Both Brazos chips though were designed specifically for the ultrathin notebook market, coming in at 9W for the Ontario chips and 18W for the Zacate APUs.
They did make appearances in the mini-mobo segment of the desktop market but didn't really take off.
Intel stole the march on AMD in terms of performance parts though with its Sandy Bridge lineup, integrating its HD 3000 and HD 2000 GPUs in with its 2nd Generation Core CPUs.
Intel's focus though was on powerful CPU parts with an improved GPU component integrated into the chip.
AMD's focus however is far more based upon jamming discrete class graphics into the same component as a decent quad-core processing part.
The Llano laptop we checked out last issue has us astounded by just how much graphical grunt AMD has managed to pack into its latest mobile APU, offering legitimate gaming performance out of a laptop that's capable of going for eight hours and costs around £600.
On the desktop though it's looking even more impressive.
The CPU component of the mobile part looked pretty weak at 1.5GHz, but on the desktop it's a far more serious setup, and for a far more reasonable price.
Around £400 for a proper DirectX 11 gaming machine, with the top-end A8-3850 Fusion APU, capable of playable framerates on a 22-inch panel?
Sign us up Mr. AMD.
AMD A8-3850 Fusion APU: Architecture
The first thing to talk about is what has actually been crammed onto this 228 sq. mm slab of silicon.
Sitting inside that unassuming package is a fully-featured quad-core CPU, based on the Stars architecture that made up the Phenom processors, a discrete-class DirectX 11 GPU and a full Northbridge too.
The normal Phenom II CPUs are around 200 sq. mm alone, with the GPUs usually around half that, so fitting all three into such a small form factor is impressive alone. When you add in the fact that it's running at around 100W for the top-end APUs, around the same as a decent quad-core CPU, it makes for one serious engineering feat.
Sadly though we're not really talking about a full Phenom II CPU, the optimised Stars architecture in the AMD A8-3850 Fusion APU actually has more in common with the Athlon II processors.
The missing ingredient is that L3 cache; the Llano Lynx APUs only come with 1MB of L2 cache per core, making a total of 4MB for the numerically challenged out there. Both the Phenom II and Athlon II carry only 512KB per core of L2 cache, but the Phenom II supplements that with a full 6MB of L3 cache shared across the CPU cores.
This AMD A8-3850 Fusion APU comes with a stock speed of 2.9GHz, making it roughly analogous with the Athlon II X4 635 processor.
It's a full-fat quad-core, though lacks the Turbo Core functionality of the lower-end Llano Lynx Fusion APUs. Still, at 2.9GHz across all cores it's plenty fast enough for general computational tasks.
It's also capable of utilising much faster memory than its Athlon II and Phenom II brethren.
It maxes out with dual channel DDR3 running at 1,866MHz, and with the new integrated GPU in this APU that faster memory makes a significant difference, but we'll come to that later.
There will be lower-end SKUs of these Llano Fusion APUs, in both A8 and A6 nomenclatures. The A8 APUs come with the top HD 6550D AMD Radeon GPU and the A6 has the weaker HD 6530D. There will be two lower-powered (65W) variations in both A8 and A6 trim with lower cock speeds but with Turbo Core enabled to take up a bit of the slack.
On the GPU side the AMD Radeon HD 6550D is a proper DirectX, discrete-class graphics chip. This top graphics part of the A8 series APUs comes with 400 unified shaders (now called Radeon Cores in response to NVIDIA's CUDA Cores), twenty texture units and eight ROPs, running at 600MHz good measure. In terms of relative discrete cards you're looking at the AMD Radeon HD 5570 levels of performance from an integrated graphics solution.
The lower-end AMD Radeon HD 6530D will then be fairly closely specced to the Radeon HD 5550, with 320 shaders, sixteen texture units and eight ROPs.
If you want to compare with the Sandy Bridge top-end graphics part, the HD 3000 (which is only available in the unlocked K-series chips) it's night and day.
The Intel part is only DirectX 10.1 compatible and is only capable of delivering around 125 GFLOPS of graphical processing power at most. The Radeon HD 6550D in this A8-3850 Fusion APU by contrast tops out at 480 GFLOPS.
To go along with the brand new APU AMD has also created a brand new desktop motherboard, with a whole new socket too. The socket is the new 905 pin FM1 and the chipset is the A-series.
The top-end chipset is the A75 with the lower-end A55 coming behind it. The only real difference is in the interfaces on offer with the more expensive part.
On the A75 you have both native 6Gb/s SATA interfaces and USB 3.0 connectivity. The USB 3.0 controller offers four sockets on the A75 boards and a full spread of six SATA 6Gb/s ports.
The A55 on the other hand is settling in the I/O dark ages with plain ol' SATA 3Gb/s and USB 2.0. But for a budget offering you're unlikely to be missing out on those pricier interfaces too much.
Though the A55 boards are unlikely to have the overclocking chops of their more expensive A75 brethren, but will offer incredibly competitive pricing.
AMD A8-3850 Fusion APU: Benchmarks
In pure CPU performance terms you can see just how much better the AMD A8-3850's four real cores are compared with the Intel Core i3 2100's twin, Hyperthreaded cores.
With the gaming benchmarks it quickly becomes obvious just how much of a benefit the AMD Dual Graphics functionality is compared to the still rather impressive stock speeds.
For the onboard GPU part of the APU to hit 25fps in DiRT 3 at High settings, with 4x Anti Aliasing turned on, is no mean feat.
The Shogun 2 CPU benchmark though shows what hit you are could be taking on the CPU side when you're taking the both the computational and graphics parts of the APU.
At the bottom though the RAM benchmark demonstrates just how much of tangible performance difference there is between different speeds of memory. Previously games wouldn't have benefited from faster RAM.
CPU rendering performance
Cinebench R11.5 – Index: higher is better
AMD A8-3850 @2.9GHz – 3.42
AMD A8-3850 OC @ 3.7GHz – 4.22
Intel Core i3 2100 @ 3.1GHz – 2.96
CPU video encoding performance
X264 – Frames per second: higher is better
AMD A8-3850 @2.9GHz – 19.96
AMD A8-3850 OC @ 3.7GHz – 24.49
Intel Core i3 2100 @ 3.1GHz – 12.76
SiSoft Sandra – GB/s: higher is better
AMD A8-3850 @2.9GHz – 15.36
AMD A8-3850 OC @ 3.7GHz – 15.58
Intel Core i3 2100 @ 3.1GHz – 17.41
DirectX 11 tessellation performance
Heaven 2.5 – Frames per second: higher is better
AMD A8-3850 on board graphics – 4.8
AMD A8-3850 Dual Graphics (HD 6670) – 13.4
AMD A8-3850 Single GPU (HD 6670) – 9.2
DirectX 11 gaming performance
DiRT 3 (Ultra, 4xAA) – Frames per second: higher is better
AMD A8-3850 on board graphics – 13
AMD A8-3850 Dual Graphics (HD 6670) – 31
AMD A8-3850 Single GPU (HD 6670) – 22
DiRT 3 (High, 4x AA) – Frames per second: higher is better
AMD A8-3850 on board graphics – 25
AMD A8-3850 Dual Graphics (HD 6670) – 58
AMD A8-3850 Single GPU (HD 6670) – 43
Shogun 2 (Medium, no AA) – Frames per second: higher is better
AMD A8-3850 on board graphics – 32
AMD A8-3850 Dual Graphics (HD 6670) – 74
AMD A8-3850 Single GPU (HD 6670) – 56
CPU gaming performance
Shogun 2 (CPU test) – Frames per second: higher is better
AMD A8-3850 on board graphics – 19
AMD A8-3850 Dual Graphics (HD 6670) – 15
AMD A8-3850 Single GPU (HD 6670) – 17
RAM gaming performance
Shogun 2 (Medium, no AA) – Frames per second: higher is better
AMD A8-3850 4GB @ 1,333MHz – 29
AMD A8-3850 4GB @ 1,600MHz – 32
AMD A8-3850 4GB @ 1,866MHz - 34
AMD A8-3850 Fusion APU: Performance
Technical specifications and impressive engineering feats are all well and good, AMD has always been pretty good at creating decent technical achievements, but not so hot at delivering performance product. Thankfully this AMD A8-3850 Fusion APU walks the walk as well.
The only real disappointment with the mobile version of Llano, Sabine, was the weakness of the actual CPU component.
In this desktop Lynx variant though you've got full, quad-core performance.
In terms of price-point it's the Intel Core i3 2100 that's squaring up against this top-end Llano at the £100 mark, and it's a comprehensive win for the AMD chip across the board.
The only place the Sandy Bridge chip can take a win is in memory bandwidth, an only then by a relatively small amount. In the CPU intensive tests, the x264 HD video encoding and Cinebench 3D rendering tests, the full four cores of the AMD APU put the dual-core, Hyperthreaded Core i3 to shame.
And you can forget about overclocking the Intel chip too, well you can up the clocks of the integrated GPU, but really, what's the point? The locked down Sandy Bridge chips wont budge an inch, but this AMD A8-3850 has got some serious overclocking chops to it.
It starts off at 2.9GHz and we managed to push it to 3.7GHz without breaking a sweat. That puts it well ahead of the Core i5 2500T, a proper quad-core Sandy Bridge CPU, albeit a low-power 45W version.
That's a more impressive overclocking performance than we've seen from an AMD processor in a long time.
The multipliers are locked down on these APUs (though the motherboard's BIOS and benching applications mistakenly reported otherwise) but the base clock of the chips will move.
What's more they'll push up the performance of the GPU component of the chip at the same time as the CPU and RAM parts. That means all-round performance goes up with the overclock.
The key component of the Llano Lynx Fusion APUs though is their graphical prowess and in that the integrated graphics do not disappoint either.
The AMD A8-3850 Fusion APU alone, paired up with an A75 board, will happily play the latest 3D games at quite playable frame rates, even if that is on more modest settings at 1680x1050 resolutions.
Surprisingly you can get pretty close to playable at HD 1080P resolutions on a few titles too.
One of the really interesting things, both for us and the DRAM manufacturers struggling with margins too, is just how much difference good memory paired up with your AMD A8-3850 Fusion APU makes. In some cases going from 1,333MHz DDR3 up to the same 4GB sticks running at 1,866MHz made for a 5FPS increase in games.
We almost managed to get Just Cause 2 into double-figures through a combination of overclock and memory tweaking. And that was at 1920x1080 on the highest settings with 4x anti-aliasing enabled, and that's no mean feat.
The difference was even more pronounced with AMD Dual Graphics enabled.
That's the new name for the AMD Fusion APU's hybrid CrossFire capabilities. Essentially you can now pair up an AMD discrete card with the onboard graphics of the APU for a serious graphical boost. The extra memory speed too can add on even more than the 5FPS we saw in the onboard graphics.
There's little point pairing the A8-3850 up with a serious graphics card, like the AMD Radeon HD 6950 though, but a modest GPU like the £75 Radeon HD 6670 is well worth a look. On its own it's not a bad card but with the Dual Graphics function enabled its performance was boosted by anything from 33% to 46%.
AMD A8-3850 Fusion APU: Verdict
We have to admit to being mildly stunned by the performance of the AMD A8-3850. It's no high-performance hero, but in terms of bang for buck there's little else that can come close to it.
The fact that both chip and motherboard can be picked up for around £200 all in is impressive, factor in a cheapo discrete AMD GPU, some decent RAM and a low-power PSU (you'll only really need 300-400W) and you've got a decent DirectX 11 gaming machine for less than £400.
It's not all good news though. As ever the early adopters are going to face a possibly frustrating time until the drivers properly mature.
Over the course of the review process new BIOS versions have appeared for a number of boards, though the Asus F1A75-V Pro has remained pretty stable all along, offering the best overclock of the two boards we've used so far.
But there have been visual artefacting both in-game and occasionally in Windows too. We've also had a few problems trying to use discrete cards on their own without the hybrid CrossFire functionality enabled. On one occasion the USB ports completely froze stopping me from using a mouse at all, even after a reboot or seven.
On the whole performance though has been solid. In raw graphical grunt terms Heaven 2.5 is a great indicator of power, and in that pairing of Radeon HD 6670 and AMD A8-3850 you've got something that's getting on par with a GTX 460. Unfortunately though that doesn't necessarily translate into real-world gaming performance.
Because the GPU is so interlinked with the CPU when it comes to graphically taxing tasks it seems to lessen the power of the processor component. This is evidenced in Shogun 2's CPU benchmark which drops significantly when you put in a discrete card for Dual Graphics.
In normal mode you're looking at 19FPS, but that drops down to 14FPS when a second GPU is dropped into the mix.
This is probably why, despite impressive raw graphical processing power giving decent Heaven scores, that doesn't translate into the same level of performance in games benches that require both GPU and CPU power at the same time.
We're also a little concerned about the lifespan of the platform itself. At Computex this year we were shown the Trinity APU, next year's Fusion offering that will incorporate discrete-class DX11 graphics with a Bulldozer CPU in the mix too.
And speaking with the likes of MSI and Gigabyte they seem pretty sure that's going to need a whole new socket again.
So you're not future-proofing yourself with this Fusion APU as the FM1 socket is unlikely to last anywhere near as long as AM3 has.
Still, for what it is it's a darned impressive offering. The chance to have such a powerful little PC for such a small outlay is rather enticing.
The AMD A8-3850 Fusion APU goes straight up against the Core i3 2100 and soundly whips it in all tests. This is a segment where AMD really has got a tangible edge over Intel for a change. The CPU performance, and overclocking capabilities especially, show up just how good it is in both raw computational terms as well as on the graphical side.
Our issue with the mobile Llano was the CPU component and with that being a real non-issue on the desktop Lynx it's an excellent new platform for AMD.
For the cost, in both monetary and wattage terms, the AMD A8-3850 Fusion APU is one impressive little beast. Cramming in decent graphical performance with excellent overclockable computational chops, in a single package, is quite a technical feat.
The Dual Graphics function makes it a bargainous base for a gaming rig too, allowing you to pair up a fairly lowly, sub-£100 AMD GPU with the Fusion APU for well over a 33% gain in gaming performance.
The memory performance too is interesting, suddenly making performance DDR3 an enticing prospect once more.
It's still not a completely rock-solid offering yet. The drivers may take a little while to mature to a point where everything's locked dow. Still, the gripes we have are relatively minor and shouldn't be a problem to iron out.
As good as the Dual Graphics function is there is still a worry that it detracts from the CPU performance side of the APU.
And the working life of the FM1 socket already seems to be the subject of some speculation too with the announcement of the Trinity APUs for next year.
We're impressed with the AMD A8-3850 Fusion APU, giving the equivalent Intel offering a kicking in both computational and especially graphical performance.