The Core 2 Quad Q8400: Intel's $183 Phenom II 940 Competitor

Final Words

It took dual-core chips falling below $200 to start increasing their prevalence in the market, and today only one of our standard CPU tests won't see a performance increase from a dual core chip. I believe we're at the beginning of that same transition for quad-core CPUs. Many of our tests show a benefit from having four cores over two but in the next two years that should change significantly. The advent of GPU computing and the impending release of Larrabee will both bring about more focus on multi-threaded development. In the coming years a new group of applications that can run on both GPUs and multi-core CPUs will cement the transistion from applications that struggle to stress more than two cores to applications that scale to a virutally infinite number of cores.

The sheer affordability of quad-core processors today is impressive; $180 - $190 will buy you a Core 2 Quad Q8400 (2.66GHz/4MB L2), a Core 2 Duo E8500 (3.16GHz/6MB L2) or a Phenom II X4 940 (3.0GHz). Whether you go dual or quad is really a personal choice depending on the types of apps you run. If you look at our SYSMark 2007 results you’ll see that the E8500 is a better choice overall. Personally I’d opt for the quad core but that’s because when I’m most performance constrained it’s in applications that scale well to four cores, but if you don't do any 3D rendering or video encoding (or heavy multitasking between two multithreaded apps) then a fast dual-core may make the most sense for you today. If you're buying for a system that you plan on keeping for 3 - 5 years however, I suspect that quad-core is the way to go.

Between the Q8400 and the Phenom II X4 940, at stock clock speeds, the 940 is the way to go unless you're very concerned about power consumption or happen to be running applications that are very well optimized for Intel's Core architecture. Update #2: Intel has just confirmed that the Core 2 Quad Q8400 does support Intel's VT-x from the start, so the update below is incorrect. The Q8300, E5400, E5300, E7500 and E7400 will also end up transitioning to versions with VT-x support as well but only the Q8400 supports it from launch. Update: As many readers have pointed out, the Q8400 does not support Intel's VT for hardware accelerated virtualization. Honestly it's silly that Intel is attempting to use VT as a profit driver at this point. Not supporting VT on any quad-core CPU just doesn't make sense. The Phenom does support AMD's hardware virtualization AMD-V, and thus gives it a tremendous leg up if you care about the feature.

If you plan on doing some light overclocking, the Q8400 has more inherent potential. Start bumping up core voltages and the Phenom II X4 940 regains strength as it's able to increase the clock speed advantage once more. Throw overclocking into the mix and the comparison isn't quite as clean cut, both AMD and Intel trade blows in their advantages. I'd say AMD would probably have more wins in our applications but at the expense of much greater power consumption.

It's good to see that there's competition here, but Intel's profit margin advantage on the Q8400 is ridiculous. AMD has to sell something Nehalem sized for under $200 to remain relevant today. I'm far less concerned about who pulls ahead while overclocked and far more concerned about AMD's health at the end of all of this. Maybe the right way of looking at this isn't by talking about a 6% performance advantage, but instead talking about whether or not you want there to be a real competitor to Intel in the future. Maybe the Phenom II X4 940 should get the win here just to ensure we have an AMD to talk about in a couple of years...