With the introduction of AM2 socket by AMD all new high-end PCs are finally using DDR2 memories. Right now the standard DDR2 speeds are 533 MHz, 667 MHz and 800 MHz, but Corsair was one of the first manufacturers to release 1,066 MHz models. These models are not only targeted to both Intel and AMD overclockers but also to regular users that have an Intel CPU running externally at 1,066 MHz and want to match the memory with the CPU external speed to achieve the maximum performance your system can deliver. Corsair has released a 1 GB kit (TWIN2X1024-8500C5, 2x 512 MB modules) and a 2 GB kit (TWIN2X2048-8500C5, 2x 1 GB modules), both with 5-5-5-15 timings. Let’s see how the 2 GB kit performs.

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Figure 1: Corsair TWIN2X2048-8500C5 2 GB DDR2-1066/PC2-8500 memory kit.

The main problem with DDR2-1066 memories today is compatibility, as only a few motherboards are able to use them to their full potential. On AMD side, as socket AM2 CPUs only support up to DDR2-800, these memories can only be used for overclocking, so there is no point of buying these modules for a socket AM2 CPU if you are not going to overclock it. For the regular user that wants to achieve the maximum system performance but without overclocking there are better solutions on the market for this platform, i.e. DDR2-800 memories with lower latencies –TWIN2X2048-6400C3 also from Corsair is a good example, as it is a DDR2-800/PC2-6400 kit where the memory runs with CL3 instead of CL5.

For the regular user that does not overclock his/her system, the main advantage of DDR2-1066 memories would be using them with Intel CPUs running at 1,066 MHz externally – for example, the new high-end Core 2 Duo and Core 2 Extreme CPUs. If you use DDR2-800 memories with these CPUs, the communication between the CPU and the memories will be taken only at half of the maximum speed it could be used. The problem, however, is that only very few socket 775 motherboards accept DDR2-1066. On almost all socket 775 motherboards your DDR2-1066 modules will run as if they were DDR2-800, even on the latest ones based on the new Intel 975X chipset.

Of course you can use your DDR2-1066 memory modules for overclocking your Intel CPU: even if your motherboard recognizes it as DDR2-800, you will have memory modules that are guaranteed to run up to 1,066 MHz.

But, just like AMD CPUs, if you don’t plan overclocking your Intel CPU and your motherboard doesn’t support DDR2-1066 but you want to have the fastest memory available, we’d recommend you to pick a low latency DDR2-800 memory, like the abovementioned TWIN2X2048-6400C3 kit from Corsair.

We decided to base our review on Intel side using a Core 2 Xtreme X6800 CPU and an ASUS P5B motherboard (Intel 965 chipset), one of the few available today supporting DDR2-1066 memories, in order to simulate the two scenarios: a regular user wanting to use DDR2-1066 instead of DDR2-800 together with a 1,066 MHz external bus (FSB) CPU and an overclocker trying to achieve the maximum clock rate with his/her memory module.

Even though the reviewed modules have official timings of 5-5-5-15-T2, you can lower these timings in order to achieve a higher performance – if your motherboard provides this option, of course. According to Corsair, you should be able to run these modules at 4-4-4-4-T1 if your run them at 800 MHz and even 4-4-4-12-T2 up to 1,080 MHz.

Unfortunately the motherboard we used didn’t provide this option (even though ASUS may release a new BIOS version enabling this feature).

Corsair provides a lifetime warranty to all their memory modules. This warranty, however, is only valid if you bought your modules directly from Corsair or from authorized resellers that are listed on their website.

Let’s now take a closer look on Corsair TWIN2X2048-8500C5 memory kit.