In this roundup, we examined three DDR2 memory modules that are certified to work at DDR2-1067, aka 533MHz. While the specifications for the three memory modules are similar, the performance tests revealed significant differences, especially with the Crucial PC2-8500 modules. Both the GSkill and OCZ modules could not be set at CL4, 500/533MHz, even with 2.40V, at least on our EVGA 680i LT motherboard. In contrast, the Crucial PC2-8500 modules could be set at CL4 and therefore, produced the best performance.
Overlooking this "problem", both the GSkill and OCZ modules were set with exactly the same memory timings. This means that their test results are directly comparable. From the results, OCZ PC2-8500 seems to be slightly faster than GSkill, at 800/1000/1067MHz. Overclocking performance was about equal, and we got 580MHz as the top speed for both modules. It's possible that with other motherboards, you could get even more MHz, but this can vary from module to module and motherboard to motherboard.
In finishing, we have no qualms about recommending both modules to all users. The Gskill F2-8500CL5D-2GBHK has a small advantage when it comes to price. You can search the retail/online stores to get the best deals on both products. Their performance should be considered about equal, and both have a lifetime warranty. They will also both help you reach high levels when you overclock your Intel C2D processor. The Crucial PC2-8500 modules were faster and better than both the GSkill and OCZ modules when it comes to overclocking, but they also cost a lot more :-)