Excerpt: Thermalright set out to pack the performance of a 120mm cooler into a 90mm package. With the Optima-90I, it looks like they've done just that. The cooling is very good with the 90mm fan and the package is relatively compact.
Conclusion: As you can see size doesn't matter, the design and implementation are what matters the most when it comes to CPU cooling. The Thermalright Ultima 90 might be small but it features big performance when it comes to cooling your hot CPU, it easily competes with coolers that are twice its size.