Shootouts

Showdown: Barcelona vs. Clovertown vs. Harpertown

By Vijay Anand - 13 Nov 2007

Under the Hood of the Barcelona - Part 2

Increased Power Efficiency for the Barcelona

Processor power management has taken significant leap from the previous generation. The native quad-core design on the Barcelona has allowed AMD to adjust the processing clock domains independently on each core depending on the utilization level, but the running voltage is still dependent on the processing state of the highest utilized core. Still, this is a step forward in power savings as the previous dual-core design pegged clock speed and voltage to that of the highest utilized core. While this reduces power consumption by modulating the clock frequencies per core, AMD finally incorporated more advanced clock-gating mechanisms to dynamically switch off sections of the die that are not needed, which is performed by analyzing the processing tasks at hand. Dubbed as the AMD CoolCore Technology, it is a purely hardware logic design that does not require any drivers on the operating system to govern its operation. Two kinds of control options are present in the CoolCore Technology, Coarse Control which regulates turning on/off large working blocks of the die like FPU or read/write logic of the memory controller, while Fine Control works at the micro level analyzing specific transistor paths, smaller logic blocks and if they can be switched off when not required.

Additionally, AMD has split the power plane in the Barcelona processor to the CPU cores from that of the memory controller, allowing them to operate at differing voltages independently. This brings about better CPU power efficiency as the processor throttles voltages up or down as required in the processing cores and the memory controller in accordance with the task at hand, which could be either a highly memory intensive operation (leaving most of the cores idle) or vice versa. With independent power planes, the operating frequencies of both domains can also be controlled separately to boost processing capacity of any one side. The flipside to this split power plane design is that you'll require an updated motherboard to take advantage of this feature, which otherwise the processor will operate off a unified power plane and loses the benefits explained. To add on, depending on the processor variant, one will incur a penalty in the memory controller's operating frequency, thus system performance is affected as well.

AMD's new Opteron codenamed Barcelona comes in the Socket-F form factor.

With the coming of a new processor design from AMD, they've also introduced a new form of power rating which they termed as ACP. TDP specs relate the absolute highest power draw possible because the processors are designed to operate within that rating. In reality, AMD found that it's not an accurate reflection to their customers who take the TDP specs to design and plan their data center / rack power needs. Average CPU Power (ACP) spec was conceived to solve this discrepancy which despite its name, the spec takes into account of the processor's real-world testing at high utilization levels in a handful of industry leading benchmarks under predefined conditions. You can read more about it in their whitepapers, but in short, the ACP specification does seem to drive a more moderate approach to measuring power considering what we normally observe in certain environments. Still, measuring processors through ACP may not be a true reflection of power consumption since it is dangerous to assume all environments are the same. Thus, the extent of manufacturers adopting AMD's new definition remains to be seen, while some considers this move by AMD to be rather desperate to make their processors look good in terms of power consumption.

With that said, here's how the various Barcelona core based processors stack up:-

AMD Opteron 23xx Series (Barcelona) Processor Details
Processor Model / Processor Characteristics Core Frequency Northbridge Frequency L2 Cache Size L3 Cache Size Max TDP (W) HyperTransport Speed Estimated Price (US$)
Opteron 2350 2.0GHz 1.8GHz 512KB x 4 2MB 95 1GHz (2000MT/s) $389
Opteron 2347 1.9GHz 1.6GHz 512KB x 4 2MB 95 1GHz (2000MT/s) $316
Opteron 2347 HE 1.9GHz 1.6GHz 512KB x 4 2MB 68 1GHz (2000MT/s) $377
Opteron 2346 HE 1.8GHz 1.6GHz 512KB x 4 2MB 68 1GHz (2000MT/s) $255
Opteron 2344 HE 1.7GHz 1.4GHz 512KB x 4 2MB 68 1GHz (2000MT/s) $209
Join HWZ's Telegram channel here and catch all the latest tech news!
Our articles may contain affiliate links. If you buy through these links, we may earn a small commission.