The Polywell Poly 939N4SLI-4000 ($3,599 as tested) is the value leader among nVidia nForce 4 SLI systems we've reviewed. It has an AMD Athlon 64 4000+ processor instead of the Athlon 64 FX-55s seen in the other SLI systems. This is not a huge drawback, since the 4000+ is the same processor as the previous generation (2.41-GHz) FX-53 CPU. The only difference is the 4000+ is locked to a 2.41-GHz clock frequency and the FX-class CPUs are easily overclockable. Using the 4000+ means the 939N4SLI-4000 gives almost the same gaming performance as the other SLI systems for a lower price.