Rack 'em up
| Processors | Cores | Architecture | Process | Clock speed | L2 cache (total) | L3 cache | Memory-controller speed | Voltage | TDP | etailer pricing |
|---|---|---|---|---|---|---|---|---|---|---|
| AMD Phenom II 940 Black Edition | 4 | K10 | 45nm | 3.0GHz | 2MB | 6MB | 1.8GHz | 0.875-1.5V | 125W | £215 |
| AMD Phenom II 920 | 4 | K10 | 45nm | 2.8GHz | 2MB | 6MB | 1.8GHz | 0.875-1.5V | 125W | £175 |
| AMD Phenom X4 9950 Black Edition | 4 | K10 | 65nm | 2.6GHz | 2MB | 2MB | 2.0GHz | 1.05-1.3V | 125W | £140 |
| AMD Phenom X4 9850 BE | 4 | K10 | 65nm | 2.5GHz | 2MB | 2MB | 2.0GHz | 1.05-1.3V | 125W | £130 |
| AMD Phenom X4 9750 | 4 | K10 | 65nm | 2.4GHz | 2MB | 2MB | 1.8GHz | 1.1-1.3V | 95W | £120 |
| AMD Phenom X4 9650 | 4 | K10 | 65nm | 2.3GHz | 2MB | 2MB | 1.8GHz | 1.1-1.3V | 95W | £112 |
| AMD Phenom X4 9350e | 4 | K10 | 65nm | 2.0GHz | 2MB | 2MB | 1.8GHz | 1.0-1.125V | 65W | £110 |
| AMD Phenom X3 8750 | 3 | K10 | 65nm | 2.4GHz | 1.5MB | 2MB | 1.8GHz | 1.05-1.25V | 95W | £99 |
| AMD Phenom X3 8650 | 3 | K10 | 65nm | 2.4GHz | 1.5MB | 2MB | 1.8GHz | 1.05-1.25V | 95W | £82 |
| AMD Phenom X3 8450 | 3 | K10 | 65nm | 2.1GHz | 1.5MB | 2MB | 1.8GHz | 1.2-1.3V | 95W | £75 |
| AMD Athlon X2 7750 Black Edition | 2 | K10 | 65nm | 2.7GHz | 1MB | 2MB | 1.8GHz | 1.2-1.25V | 95W | £65? |
| AMD Athlon X2 7550 | 2 | K10 | 65nm | 2.5GHz | 1MB | 2MB | 1.8GHz | 1.2-1.25V | 95W | £55? |
| AMD Athlon X2 6400+ BE | 2 | K8 | 65nm | 3.2GHz | 2MB | N/A | 1GHz | 1.35-1.4V | 125W | £72 |
| AMD Athlon X2 6000+ | 2 | K8 | 65nm | 3.1GHz | 1MB | N/A | 1GHz | 1.1-1.4V | 89W | £63 |
The list shows a number of AMD desktop CPUs, correct as of January 8th, 2009.
45nm, and more cache
A (successful) move to a smaller manufacturing process is a very good thing with respect to CPU production. Shrinking the bulk of the processor's transistors to a smaller size means that, ceteris paribus, you can shoehorn more CPU cores on to a given-sized wafer. Conveniently ignoring yield values and simplifying hugely for a moment, AMD is thus able to produce more chips than before, lowering per-CPU overheads. Intel's been doing this for some time, of course.
A second benefit of a smaller process is that the transistors, being, well, smaller, need less switching voltage to operate at a given frequency. That, in a nutshell, is why new process introductions rarely, if ever, breach the TDP associated with the erstwhile production, and it allows a company to ramp up clock-speeds yet still keep within thermal tolerances established on previous-generation models.
However, Intel and AMD tend to add more mojo to the architecture with the shrink in process. Why? Because it's an opportune time to reinvestigate how best to gain overall performance for a given die-size.
AMD's taken on the benefits of the 45nm manufacturing process, based on immersion lithography, and decided to reduce die-size by around 10 per cent - 285mm² for 65nm Phenom X4 and 258mm² for 45nm Phenom II - but has increased the transistor count from around 450m to a not-unsubstantial 758m.
A smaller die-size and vastly higher transistor-count seem to be oxymoronic at first glance, but can be explained by the fact that 45nm transistors are around half the size of 65nm, and AMD's decision to add 4MB of L3 cache to Phenom IIs makes up, for the most part, the rest.
Extra on-chip cache is a relatively straightforward, if die-expensive, method of gaining a little bit of extra performance. Just how potent it is depends upon the workload in question, and we'll investigate just how much it adds when looking at performance numbers.
Note, however, that AMD's Phenom-based L3 cache runs at the same speed as the northbridge and not at core speed. The new CPUs operate with L3 running at a 1.8GHz out of the box.
Faster clocks
When launched, we had high hopes that AMD's 65nm Phenoms, roughly analogous to Intel Core 2 Quads in clock-for-clock performance, would scale to 3GHz, quickly, keeping the chip giant honest in the high-range space.
Unfortunately, for reasons detailed on the previous page, that never happened, and 2.6GHz - Phenom X4 9950 BE - was the fastest speed at the start of this year. Air-based overclocking pushed certain B3 Phenoms past 3GHz, but it wasn't guaranteed by any means.
Now, 3GHz is finally being delivered with the Phenom II 940, along with the 2.8GHz-clocked Phenom II 920, making the range-topping model some 15 per cent faster than the 9950 BE. Taking into account the new process, reports have indicated that 3.6GHz+ is achievable on air-cooling with esoteric setups managing 5.5GHz+.
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