AMD’s Triple Core Phenom
In theory, really nothing is wrong with three cores, but it only takes a look at Microsoft’s Vista to find out that DRM paranoia has not stopped at anti piracy but has also included special precautions against odd numbers of CPU. That is, a Vista license in its native form can only work on CPUs coming in the power of 2. Luckily, Microsoft has published a hotfix to address this licensing issue and allow the use of three cores. Well, it is not quite that easy, getting the hotfix requires submitting an online request that is then answered via email by Microsoft to reveal the download location and password necessary to extract the compressed file. It took about 4 hours for Microsoft to reply to our email BEFORE the triple cores were released to the public – well within the 8 business hours response period posted by Microsoft on their website. After the official release of the X3 processors into the retail channel, we checked again and the response was emailed by Microsoft after 4 hours – again within the claimed time of response. Keep in mind that the patch is not elementary for the operation of the X3 processor, all it does is increase the number of cores allowed by Vista (or Server 2008) from two to three. Intriguingly, Windows XP does not have any licensing problems with the triple core design, yet another reason to stick with XP, regardless of what fire-sale Microsoft has on Vista licenses.
The next question is, if the OS does not support three cores without patch, what can we expect from the different software applications. Is the number of threads going to be limited by the power of 2 and if so, which power of 2 are we going to be looking at? The reason to ask this question is very simple. Numerous software applications have the naughty tendency of just defaulting to a single thread if there is any unknown variable in the CPUID – like the number of cores that is supported. To make a long story short, it did not take very long to find exactly this issue in some of the most commonly used software out there, we’ll get to those data in just a bit.
X3 Peculiarities
Within the X3 design, everything tied to one core is present in triplicate. Naturally, this includes the L1 data and instruction caches that in the X3 series now amount to a total of 384 kB as opposed to 256 kB in the X2 processors or the 512 kB in the X4 series. Likewise, the L2 cache is now 1.5 MB as opposed to the 1MB or 2 MB in the Athlon X2 series or Phenom X4, respectively. Note though that the L3 cache is not part of the actual core design but rather a feature of the so-called NorthBridge also featuring the memory controller and running on its own supply voltage circuitry and frequency. Therefore, regardless of whether it is an X3 core or an X4 core, the cache is always 2 MB.
With respect to the naming convention, all X4 processors will be part of the 9000 series whereas the X3 versions will all start with an 8 in the four digit part number.
AMD Phenom X4 8x50 processor TECH SPECS:
| Processor Frequency: | 2.1, 2.3, 2.4GHz |
| L1 Cache Sizes: | 64K of L1 instruction and 64K of L1 data cache per core (384 KB total L1 per processor) |
| L2 Cache Sizes: | 512KB of L2 data cache per core (1.5 MB total L2 per processor) |
| L3 Cache Size: | 2 MB |
| Memory Controller Type: | Integrated dual 64-bit wide memory controller * |
| Memory Controller Speed: | 1.8 GHz with Dual Dynamic Power Management |
| Types of Memory Supported: | Support for unregistered DIMMs up to PC2 8500 (DDR2-1066MHz) |
| HyperTransport 3.0: | One 16-bit/16-bit link @ up to 4.0GHz full duplex (2.0GHz x2) |
| Total Processor Bandwidth: | Up to 33.1 GB/s bandwidth |
| Packaging: | Socket AM2+ 940-pin organic micro pin grid array (micro-PGA) |
| Fab location: | AMD's Fab 36 wafer fabrication facilities in Dresden, Germany |
| Process Technology: | 65-nanometer DSL SOI (silicon-on-insulator) technology |
| Approximate Transistor count: | ~ 450 million (65nm) |
| Approximate Die Size: | 285 mm2 (65nm) |
| Max Ambient Case Temp: | 61o Celsius |
| Nominal Voltage: | 1.2-1.3 Volts |
| Max TDP: | 95 Watts |
Power Consumption
Three cores should use less power than four but the power consumption of the Phenom series of CPU is a composite figure with the individual cores and the NB+L3 cache each contributing. Keep in mind that the split voltage plane provides AMD with a means to throttle the cores in frequency and voltage while keeping the NB+L3 cache running at full power. Realistically there is no way around this, since AMD's CPUs can throttle on a per core basis but that also requires that if any core is running under load, the memory controller and cache will have to do the same, regardless of what the other cores are doing at the same time.
Max Power
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