Two months ago when we tested the top desktop Bulldozer processor, we concluded that it turned out a big disappointment. The results of our today’s FX series testing, including lower-cost CPU modifications, didn’t change out opinion. Processors on Bulldozer microarchitecture with four or six cores are designed exactly the same way as their eight-core counterparts. Pairs of cores are combined into modules and share some of the resources. And even though this approach can be implemented at a lower transistor count and allows producing relatively inexpensive monolithic semiconductor dies, the actual performance-per-core drops making the final product not so well-balanced in the end. As a result, AMD can sport many processor cores, but in reality this number doesn’t mean anything. Our tests showed that a pair of Bulldozer cores can compare in performance only against one Sandy Bridge core, and only with certain allowances and only in applications that split the load in parallel threads. This is where the low performance in most applications comes from.
The flagship eight-core CPU in the FX family, AMD FX-8150, in most cases can’t catch up even with the quad-core Core i5-2500, performing well only in few selected applications for 3D modeling and during video transcoding.
Slower eight-core modification, AMD FX-8120, looks even less convincing, because it has significantly lower clock frequencies. In terms of performance, this processor ranks even below the quad-core competitor solutions. Moreover, FX-8120 is also slower than the top previous-generation AMD CPU – Phenom II X6 1100T.
