We already had the OCZ PC4000 XTC working at 500MHz with some BIOS changes, but we needed to go even higher than the SPD frequency to see just how high the OCZ modules could go. To do this, we used the ASUS A8N-SLI Premium motherboard, but we had problems going above 525MHz, most probably because the ASUS motherboard cannot offer more than 3.0v to the RAM modules.
We also tried a DFI LAN Party SLI motherboard, and we fired the OCZ memory with 3.6v. The OCZ PC4000 was running smoothly, even at this high voltage, and the modules were slightly hot to touch. We should also add that we did not provide any extra RAM cooling.
The highest stable operating frequency that we managed to get was 580MHz (2x289.8MHz), which was even higher than the overclocked frequency we had with Mushkin (577MHz). However, we had to increase timings to make the memory stable. The stability of the modules was checked with MemTest and Prime95.
Especially with Prime95, we had the system running for almost 2 days continuously and we had no errors. We then re-ran all the tests to see how if there was ny gain with the modules overclocked.
All tests showed a clear improvement in performance, but always keep in mind that we had the memory running at 3.6v, which is voltage hungry. The OCZ PC4000 XTC Platinum Edition is an excellent overclocker, but also a very good performing memory as it is. If you want to buy memory modules to do some serious overclocking, these have to rank among the best.