Core-by-Core System Power Draw
 Will stripping out the L3 cache have a big impact on power
draw?
While the AMD "Deneb" die that's used in AMD's Phenom II processors is rated at 140W TDP, the "Propus" die requires significantly less power because
it's a smaller chip overall, and doesn't have a power-sucking L3 cache
to boot. The Athlon II X4 620 is rated for a 95W TDP.
To determine how much power multi-core processors draw,
PCSTATS will be measuring total power consumption what the CPU is in idle and
several CPU-stressed states. To get an accurate measurement, it's necessary to
disable AMD and Intel's power saving and CPU clock speed throttling technologies
like Cool 'n' Quiet, EIST (speedstep) and C1E power states. To simulate single-core
load a program called Stress
Prime (SP2004) is
used.
PCSTATS set about stressing each processor from one to all cores. This programs
gives better insight into different power draw scenarios. The SP2004 program is
multi-threaded, allowing individual CPU cores to be stressed by each instance of the
program.
Total system power consumption
was read with the Extech Power Analyzer Datalogger (model 380803). The Extech
Power Analyzer is located between the main 120AC supply and the PC's power
supply.
| Total System Idle
Power Draw |
| Processor |
Total System Power Draw |
| Intel Pentium 4 540 |
   150 Watts |
| Intel Pentium D 840 |
165 Watts |
| Intel Pentium D 940 |
168 Watts |
| Intel Core 2 Duo E6600 |
117 Watts |
| Intel Core 2 Duo E6750 |
123 Watts |
| Intel Core 2 Duo E8400 |
131 Watts |
| Intel Core i7 920 |
144
Watts |
| AMD Sempron 3600+ |
   120 Watts |
| AMD Athlon64 4000+ |
163 Watts |
| AMD Athlon64 FX-60 |
127 Watts |
| AMD Athlon64 X2 4800+ |
143 Watts |
| AMD Athlon64 X2 5000+ |
156 Watts |
| AMD Athlon64 FX-62 |
168 Watts |
| AMD Athlon II X2 250 |
128
Watts |
 AMD Athlon II X4 620 |
  130 Watts |
| AMD Phenom II X3 720 |
155 Watts |
| AMD Phenom II X4 955 |
148 Watts |
| AMD Phenom II
X4 965 |
154 Watts |
At idle, there's already some substantial reductions in power draw
from AMD's top-of-the line processors. The Athlon II X4 620 PC system draws the
least amount of power out of the quad-core CPU based PCs in this chart.
| Total System Stressed Power
Draw - All Cores/Threads |
| Processor |
Total System
Power Draw (All Cores) |
| Intel Pentium 4 540 |
223 Watts |
| Intel Pentium D 840 (2 Core ) |
240 Watts |
| Intel Pentium D 940 (2 Core Load) |
253 Watts |
| Intel Core 2 Duo E6600 (2 Core Load) |
156 Watts |
| Intel Core 2 Duo E6750 (2 Core Load) |
163 Watts |
| Intel Core 2 Duo E8400 (2 Core Load) |
158 Watts |
| Intel Core i7 920 (8 Thread Load) |
213 Watts |
| AMD Sempron 3600+ |
148 Watts |
| AMD Athlon64 4000+ |
172 Watts |
| AMD Athlon64 FX-60 (2 Core Load) |
196 Watts |
| AMD Athlon64 X2 4800+ (2 Core Load) |
173 Watts |
| AMD Athlon64 X2 5000+ (2 Core Load) |
207 Watts |
| AMD Athlon64 FX-62 (2 Core Load) |
235 Watts |
| AMD Athlon II X2 250 (2 Core Load) |
163 Watts |
| AMD Athlon II X4 620 (1
Core Load) |
 148 Watts |
| AMD Athlon II X4 620 (2
Core Load) |
167 Watts |
| AMD Athlon II X4 620 (3
Core Load) |
187 Watts |
| AMD Athlon II X4 620 (4
Core Load) |
195 Watts |
| AMD Phenom II
X3 720 (3 Core Load) |
213 Watts |
| AMD Phenom II X4 955 (4 Core Load) |
236 Watts |
| AMD Phenom II X4 965 (4 Core Load) |
264 Watts |
Once all four cores are fired up, the AMD Athlon II X4
620 processor remains the most power efficient quad-core, with just 195W total
system draw under a full load. A large part of this is likely due to the
absence of the L3 cache, but a lower clockspeed will also have an impact on
overall power consumption.
Overclocking is up next, just how fast can PCSTATS push the Athlon
II X4 beyond 2.6GHz? I think 1GHz is doable, how about 2GHz?
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