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Intel Core2 Quad Q8400 vs AMD Athlon II X4 651 Quad-

The AMD Athlon II X4 651 Quad-Core is newer than Intel Core2 Quad Q8400 @ 2.66GHz and is around 17% faster in multi-threaded (CPU Mark) testing. The AMD Athlon II X4 651 Quad-Core is around 11% faster in single-thread testing. Both CPUs operates at simliar power levels (TDP). All the CPUs in this comparison belong in the Desktop CPU Class. The values below were tabulated from a combined 1790 benchmarks submitted from our PerformanceTest software and results and are updated daily to include new submissions.

  • The first section will show basic information for each CPU selected.
  • The additional graphs shows the CPU Mark and Single Thread values of each CPU selected.
  • An accompany graph, if price data is available, will shows the value for money, in terms of the CPU Mark/Thread Rating per dollar.
  • The last section will show approximate yearly running costs for the CPUs.

×Intel Core2 Quad Q8400 @ 2.66GHz×AMD Athlon II X4 651 Quad-Core+ ADD
Price Search Online Search Online
Socket TypeLGA775FM1
CPU ClassDesktopDesktop
Clockspeed2.7 GHz3.0 GHz
Turbo SpeedNot SupportedNot Supported
# of Physical Cores4 (Threads: 4)4 (Threads: 4)
CacheL1: 256KB, L2: 4.0MB, L3: 0MBL1: 512KB, L2: 4.0MB,
TDP95W100W
Yearly Running Cost$17.34$18.25
Other
First Seen on ChartQ2 2009Q1 2012
# of Samples1676114
CPU Rank35363305
CPU Value16.116.2
Single Thread Rating(% diff. to max in group)1143(-10.0%)1269(0.0%)
CPU Mark(% diff. to max in group)2081(-14.5%)2433(0.0%)
1 - Last seen price from our affiliates NewEgg.com & Amazon.com.

CPU Mark Rating
As of 7th of February 2026 - Higher results represent better performance
Intel Core2 Quad Q8400 @ 2.66GHz
2,081
AMD Athlon II X4 651 Quad-Core
2,433
PassMark Software © 2008-2026
CPU Value (CPU Mark / $Price)
As of 7th of February 2026 - Higher results represent better value
Intel Core2 Quad Q8400 @ 2.66GHz
16.1
AMD Athlon II X4 651 Quad-Core
16.2
PassMark Software © 2008-2026
CPU Single Thread Rating
As of 7th of February 2026 - Higher results represent better performance
Intel Core2 Quad Q8400 @ 2.66GHz
1,143
AMD Athlon II X4 651 Quad-Core
1,269
PassMark Software © 2008-2026
Estimated Energy Usage Cost
Estimated Energy Adjustable Values
Average hours of use per day Average CPU Utilization (0-100%)1 Power cost, $ per kWh2
8
25
1Average user usage is typically low and can vary from task to task. An estimate load 25% is nominal.
2Typical power costs vary around the world. Check your last power bill for details. Values of $0.15 to $0.45 per kWh are typical.
Intel Core2 Quad Q8400 @ 2.66GHz AMD Athlon II X4 651 Quad-Core
Max TDP95W100W
Power consumption per day (kWh)NANA
Running cost per dayNANA
Power consumption per year (kWh)NANA
Running cost per yearNANA
Shown CPU power usage is based on linear interpolation of Max TDP (i.e. max load). Actual CPU power profile may vary.