AMD 780G chipset review

Quiet, compact and yet extremely capable. That's the recipe for a great home theatre PC. Getting hold of the right ingredients is another matter, however. Especially if pricing is a sensitive issue for you.

But what if there was a genuine HD-ready HTPC platform that combined motherboard and CPU for just £100? Enter AMD's new affordable, efficient and HD-optimised 780G PC platform. It really does look like the killer home theatre solution we've been waiting for.

AMD's new 780G chipset

The key components include AMD's latest mainstream 780G motherboard chipset, complete with fully DirectX 10 compliant integrated graphics, and a new low-power variant of its Athlon 62 X2 dual-core CPU.

Startlingly low power consumption, full hardware decode for high definition video disks (i.e. Blu-ray) and a revolutionary leap in integrated graphics performance are just some of the bullish claims AMD has been making for the new platform. Then again, AMD seemed pretty damn confident about the Phenom quad-core processor in the lead up to launch late last year. And we know how that turned out...

With all that in mind, we're much more intrigued than we otherwise might be. Does this mainstream computing solution, which majors on features and efficiency rather than outright grunt, truly have what it takes to deliver a great high definition experience?

Mainstream multimedia machine

On paper, there's little doubting that the 780G motherboard chipset has one of - if not the - most comprehensive feature sets of any mainstream integrated solution. Socket-wise, we're talking AM2+. That translates into support for all the latest AMD processors, including single, dual and quad-core chips.

Memory support takes in various flavours and speeds of DDR2. The specifics depend on the processor you plump for (remember, AMD CPUs have integrated memory controllers). But whatever the case, odds are it'll be cheap. DDR2 prices have hit rock bottom.

In terms of expansion and ports, 780G is largely predictable. Support for discreet graphics is provided by 16 full speed PCI Express 2.0 lanes, with a further four for additional peripherals.

Where it does differ from the norm is the full compliment of digital and analogue video connections. Along with good old VGA, the 780G is wired up to provide DVI, HDMI and DisplayPort video outputs. Add in HDCP compliance and you have an affordable PC platform that ticks all of our HD boxes.

By the power of Radeon

Much of the 780G's multimedia prowess is thanks to its Radeon HD 3200 graphics core.

Despite the name, it's actually virtually identidal to the Radeon HD 2400, AMD's entry level discreet offering of around one year ago. With 40 stream processors and the capability to pump four pixels per cycle, on paper it's comfortably the most powerful integrated 3D graphics core yet.

Perhaps more importantly, it also includes AMD's swanky UVD 2D video decode engine. The big news here is hardware decode of all the key HD video codecs including MPEG2, AVC (H,264) and VC-1.

To put it another way, AMD reckons the this chipset is capable of offload much if not all of the work involved in decoding high definition movie disks from the CPU. Which in turn allows the use of a cheaper, cooler running and less powerful processor.

The Radeon HD 3200's other headline grabbing new feature is Hybrid Crossfire. It boils down to the ability to boost 3D performance by pairing up a low-powered discreet graphics chip with the Radeon HD 3200 core in dual-GPU Crossfire rendering mode. Currently, only the distinctly low-end Radeon HD 3450 and 3470 add-in cards are compatible with Hybrid Crossfire.

As for the new Athlon 64 4850e CPU, it's a dual-core chip with an exceptionally low 45 Watt power rating. Despite that, it boasts a healthy 2.5GHz peak operating frequency along with twin 512K L2 cache memory pools. Think of it as a low power Athlon 64 X2 4800+ and you'll get the idea.

Real world performance

Our first hands-on with the 780G platform comes courtesy of a Gigabyte micro-ATX motherboard, the memorably-monikered GA-MA780GM-S2H.

As you'd hope for an HTPC-centric board, it's entirely passively cooled and hence essentially silent. Expansion wise, a single PCI-E 16-lane graphics port along with a further single-lane PCI-E socket and a pair of old school PCI slots is your lot. Which, frankly, is fine given that the board already has pretty much all you'll ever need.

There are five internal SATA ports, a single eSATA external socket, integrated HD audio and firewire. Video out is amply covered with HDCP-compliant DVI and HDMI ports as well as analogue VGA.

But what about performance? Well, the bad news is that 3D grunt remains pretty dire. Granted, the integrated Radeon HD 3200 core is the best of its kind, but it still can't cope with modern PC games even at modest resolutions like 800 x 600 pixels.

Unless, that is, you are willing to suffer average frame rates under 15 per second, which is all you can hope for in the likes of Call of Duty 4. That's the texture quality crushed to a blurry mush. You can totally forget about goodies like anti-aliasing.

Add a discreet HD 3400 series card in Hybrid Crossfire mode and things do improve. But the progression is from painful to extremely mediocre. Make no mistake, you'll need to drop in a decent add-in 3D card if you want to experience real gaming pleasure.

High definition goodness

Elsewhere, the news is better. Running our H.264 high bitrate 1080p test video clip in PowerDVD 7.3, CPU utilisation is reduced from around 90 per cent running purely on the CPU to approximately 50 per cent with the aid of the UVD engine. In other words, the 780G is capable of liquid smooth HD playback with plenty of CPU resources in reserve.

As for general computing performance, memory bandwidth was a little weak for an AMD paired with 800MHz DDR2 at 6.4GB/s. But otherwise our video encode and professional rendering tests pumped out results within spitting distance of what you'd expect from a high performance motherboard running the same CPU. Well, one that supports AMD chips at least. If it's raw performance you crave, Intel's chips currently have the edge.

But if the combined grunt of the 780G chipset and 4850e CPU is unexciting, try this for size. At idle the entire platform - chipset, graphics core, CPU, memory, the lot - consumes just 53 Watts. Even under peak processor load it tops out at 101 Watts. That's a great characteristic for a platform designed to run inconspicuously in the background.

Oh and by the by, the 780G is compatible with AMD's rather tasty OverDrive application. It's a super snazzy Windows-based overclocking tool that shows the industry just how this sort of thing should be done.

By now, you may be getting the impression that we like the 780G and AMD's latest low power Athlon 64 X2. Indeed we do, it's a superb cut-price HTPC solution which we highly recommend. But do yourself a favour. Ignore the Hybrid Crossfire gimmickry.

Gigabyte GA-MA780GM-S2H

Price: £55

Processor support: Socket AM2/AM2+ Athlon and Phenom

Chipset : AMD 780G

Graphics: Radeon HD 3200

Memory support : DDR2 up to 1,066MHz

Expansion: PCI-E 16-lane, PCI-E single-lane, 2x PCI

Video out: DVI, HDMI, VGA

Storage I/O: 5x SATA, 1x eSATA, 1x PATA

Other: 8-channel HD audio, LAN, PS/2

AMD Athlon 64 X2 4850e

Price: £40

Socket: AM2/AM2+

Clockspeed : 2.5Ghz

Bus: 1GHz HT

Cache memory: 2x 512k L2

System memory support: DDR2 up to 800MHz