How does it stack up
Other optimisations and pragmatism
As one would expect, the Phenom carries over the K8's 64-bit processing but expands upon the ISA to include what it terms as SSE4a. Note, though, that SSE4a only contains two new instructions (MOVNTSS and MOVNTSD - writing 32/64 bits directly into memory for fast stores) that aren't found in Intel's 47-instruction SSE4.1.AMD is implementing HyperTransport 3.0 as the conduit between processor and chipset. HT3.0 provides a 16-bit link operating at an effective 3600MHz. Adding it up, there's 14.4GiB/s for I/O-related tasks, up from the 8GB/s for K8, giving the processor a total 31.4GiB/s throughput compared to the K8's 20.8GiB/s. The Phenom is backwards-compatible with compliant motherboards featuring HT1.0 and 2.0, of course. Note, though, that Phenom features a single HyperTransport link rather than multiple links present in the server/workstation Barcelona part.
Phenom is more than two K8 processors on a single die - a number of logical and performance-enhancing features have been integrated into the quad-core design.
Shaping up?
The Phenom processor will ship in a regular AM2 form-factor but not all of its feature-set will be available to present AM2 motherboards. Users of such boards won't enjoy the benefits of DDR2-1066 compatibility, HyperTransport 3.0 or dual-plane power-switching - where processor and memory-controller are run at different voltages.
To take advantage of these features one must use an AM2+ motherboard and that, of course, is why AMD is also releasing a new core-logic today. But let's not get ahead of ourselves.
Better than Intel Core 2 Quad?
Taking the numerous performance-adding features into account, one can surmise that AMD's quad-core Phenom should perform somewhere in the vicinity of Intel Core 2 Quad processors of the same clock speed. The important questions, then, are what speed-grades the Phenom is launching at and just how do their prices compare to Intel's?
D denotes delicious or defficient?
Socket AM2+, clearly.
Facts and figures
Three quad-core Phenom processors were scheduled to be launched today - the 2.0GHz-clocked Phenom 9500, 2.2GHz Phenom 9600 and 2.4GHz Phenom 9700. However, at the last minute, AMD pulled the release of the Phenom 9700 for reasons that we have still to fathom. We can only surmise that it had significant issues in speed-binning parts at that speed and chose to run with the two lower-clocked models instead. Phenom 9700 will now launch in Q1 2008, we're informed, putting a significant dampener on the AMD roadmap for 2007.
| Processors | Clock speed | L2 cache (total) | L3 cache | Voltage | TDP | Price |
|---|---|---|---|---|---|---|
| AMD Phenom 9700* | 2.4GHz | 2MiB | 2MiB | 1.25V | 125W | ? |
| AMD Phenom 9600 | 2.3GHz | 2MiB | 2MiB | 1.2V | 95W | £159 (£180 as at 20/11) |
| AMD Phenom 9500 | 2.2GHz | 2MiB | 2MiB | 1.2V | 95W | £145 (£160 as at 20/11) |
* - now rescheduled for Q1 2008.
The two released quad-core Phenom processors have the same architectural underpinning but the 9600 will be released with an unlocked multiplier, we were informed at last minute.
The Phenom name will initially refer only to quad-core models, such as those reviewed here. But AMD will be introducing tri-core variants in Q1 2008 and dual-cores in Q2 2008 - all based on the same underlying K10 architecture.
The initial processor line-up is quite telling. There is no FX-edition CPU headlining the range for enthusiast with deep pockets to tinker with. AMD will release a 2.6GHz-clocked Phenom 9900 along with the 9700 in Q1 next year.
AMD is a year late to the quad-core party, so its selling story will have to be about pricing, rather than performance. If AMD was able to launch a 3.0GHz Phenom right now, it certainly would - and that processor would challenge the Intel Core 2 Extreme QX9650 for the title of heavyweight desktop champion of the world. As it is, AMD's has had to bring the fight on value grounds.
We already know that the obvious competitor, the 2.4GHz-clocked Intel Core 2 Quad Q6600 (£165) is priced at artificially low levels. AMD's having to match Intel's pricing with its range-topping part, so not only does Intel have the performance lead at the very high end, it's able to pre-empt and squeeze AMD's margins at the lower end of the quad-core spectrum. AMD would love to charge £300 for the Phenom 9600 but the Q6600's pricing effectively stops it from doing so.
Here's our engineering-sample Phenom processor that we received less than a week ago. Note how it's natively clocked in at 2.4GHz? That speed has now been binned for immediate release, of course.
Competitive comparison
| Processor name | AMD Phenom 9600 | AMD Athlon 64 X2 6400+ | Intel Core 2 Quad Q6600 | Intel Core 2 Duo E6850 |
|---|---|---|---|---|
| Form factor | AM2+ (940-pin) | AM2 | LGA775 | LGA775 |
| Manufacturing process | 65nm | 90nm | 65nm | 65nm |
| Die size | 285mm² | 219mm² | 286mm² (2 x 143mm) | 143mm² |
| Transistors | 450m | 243m | 582m | 291m |
| Physical cores | 4 | 2 | 4 | 2 |
| Inst. per clock | 3 | 3 | 4 | 4 |
| Pipeline stages | 12 | 12 | 14 | 14 |
| Clock speed | 2.3GHz | 3.2GHz | 2.4GHz | 3.0GHz |
| FSB/HT clock | 200MHz | 200MHz | 266MHz | 333MHz |
| Memory support | DDR2, 1066MHz, DC, ganged, un-ganged | DDR2, 800MHz, DC | DDR2/3, 800MHz/1066MHz, DC | DDR2/3, 800MHz/1066MHz, DC |
| L1 cache total | 128KiB data + 128KiB code | 128KiB data + 128KiB code | 128KiB data + 128KiB code | 64KiB data + 64KiB code |
| L2 cache total | 2MiB (512Kib per core) | 2MiB | 8MiB | 4MiB |
| L3 cache | 2MiB | N/A | N/A | N/A |
| ISA | x86, x86-64, SSE-SSE4a | x86, x86-64, SSE-SSE3 | x86, x86-64, SSE-SSSE3 | x86, x86-64, SSE-SSSE3 |
| TDP | 95W | 125W | 95W | 65W |
| Operating voltage | 1.1-1.25V | 1.3-1.35V | 1.2-1.3625V | 0.965-1.35V |
| Current price | £159 (£180 as at 20/11) | £129 | £165 | £135 |
We've deliberately omitted the higher echelons of Intel's Core 2 Quad line-up; AMD's pricing ensures that it's not competing there at all. We're looking at processors' pricing that varies between £129 and £165 - pretty affordable expenditure, you might say.
Summary
Our technical overview of AMD's quad-core Phenom processor has highlighted a number of advancements in power and efficiency over its previous-generation CPUs. However, the Phenom's biggest stumbling block, from an architecture's point of view, will be the three-issue width of the core and it's here that Intel will eke out a performance advantage on a clock-for-clock basis.
We're ambivalent, though, about whether a quad-core processor is native - as in AMD's design or a botch-job, as AMD would like us all to think of Intel's glue-them-together approach. But what we do care about is performance and form-factor longevity.
The Phenom's 9600 lowly clock-speed of just 2.3GHz will compromise its ability to beat out the slowest Intel Core 2 Quad. Again, in case you missed it, AMD would release faster Phenoms right now if it could.
Now let's discover whether AMD's enhancements can provide tangible performance benefits, especially when compared to the competition's erstwhile quad-core processor that was launched over a year ago.
