DDR:
This stands for Double Date Rate and that means it doubles the bandwidth of the memory by transferring data twice as fast on both the rising and falling of the clock cycle. 

CAS (tCL):
This stands for Column Address Strobe or Column Address Select and that essentially means the number of cycles for the memory to get information and then process that information. Also keep in mind that a lower CAS is much better than a higher CAS, so try and keep CAS as low as possible when overclocking. 

tRCD:
This is the delay from the time a row is activated to when the cell (or column) is activated via the CAS signal and data can be written to or read from a memory cell. When memory is accessed sequentially, the row is already active and tRCD will not have much impact. However, if memory is not accessed in a linear fashion, the current active row must be deactivated and then a new row selected/activated. In such an example, low tRCD's can improve performance. However, like any other memory timing, putting this too low for the module can cause instability.

tRP:
RAS Precharge; the time required to switch from one row to the next row. For example: switching internal memory banks.

tRAS:
Memory architecture is like a spreadsheet with row upon row and column upon column, with each row being one bank. For the CPU to access memory, it first must determine which row or bank in the memory is to be accessed and then activate that row with the RAS signal. Once activated, the row can be accessed over and over, until the data is exhausted. This is why tRAS has little effect on overall system performance but could impact system stability if set incorrectly.

tCLK:
This is simply the clock used for the memory. Note that because frequency is 1/t, if memory were running at 100Mhz, the timing of the memory would be 1/100Mhz, or 10nS.

EPP:
This stands for Enhanced Performance Profiles and is a new approach that simplifies overclocking and ensures memory and platform compatibility. This technology was defined to utilize the extra space in the EEPROM to store memory configuration settings that are sufficient to optimize and maximize the performance of a memory module. It basically auto detects your motherboard's chipset and sets the memory timing accordingly. While EEP is nice, many overclockers will be manually adjusting their memory in the motherboard's BIOS.

This memory is also Dual Channel which means better overall memory bandwidth resulting in superior performance. In order to benefit from this technology you will need to have a dual channel motherboard. Non-dual channel motherboards do not have two fully independent 64-bit memory controllers, but dual channel boards do which means they have a 128-bit memory interface. They can be installed singly, but obviously performance will be much less at the same MHz.

Please remember that this memory is DDR2 and it does differ from DDR memory in a number of ways. Please note that DDR2 memory is the new memory standard for today's motherboards. The following explanation below goes over the general differences. It does not take into account some of the faster DDR/DDR2 memory on the market, but it is designed to help you distinguish between the two:

To begin, the maximum Data Rate is different (400MHz for DDR vs. 667MHz for DDR2), Bus Frequency (200MHz vs. 333MHz), DRAM Frequency (200MHz vs. 166MHz), Package Type (TSOP-II vs. FBGA), Voltage (~2.5 vs. 1.8), Prefetch Size (2 bits vs. 4 bits) and a CAS Latency (which varies quite a bit but in general 2.5 for DDR vs. 4 for DDR2 memory). The on-die termination is different as well. To eliminate signal noise, DDR uses transistors that are on the motherboard whereas for DDR2 it�s on each memory chip. The Off Chip Driver Calibration on DDR2 memory also increases signal integrity.

While 240-pin DDR2, 184-pin DDR and the older style 168-pin DIMM memory are all approximately the same size, the 240-pin DIMMs and 184-pin DIMMs have only one notch within the row of pins. The notch in a 240-pin DDR2 DIMM is slightly more toward the center of the module. Please keep in mind that DDR2 memory is not backward compatible and will only fit motherboards specifically designed for it.

Details Specifications:
Speed: PC2-6400 or 800MHz DDR2 (400MHz)
Size: 1024MB Modules and 2GB (2x1024) Dual Channel Kits
P/N: OCZ2RPR800EB2GK
Latency: EPP 4-3-3-15*
Package Type: 240 DIMM
Heat Spreader: Reaper HPC Heatsink**
Voltage: 2V (2.2V EVP***)
Warranty: OCZ Lifetime Warranty

* NVIDIA nForce 680i chipset ONLY

**The Reaper HPC series uses heat pipe technology to rapidly remove heat from the main body of the memory modules and conduct the thermal load to the extended radiator fin array. The addition of the extended fin array nearly doubles the total surface area available for heat dissipation while the heat pipes warrant near isothermicity throughout the entire design. The result is a doubling in effective heat dissipation at equal delta t or, in real systems, a significantly lower operating temperature of the memory modules.

***OCZ EVP (Extended Voltage Protection) is a feature that allows performance enthusiasts to use a VDIMM of 2.2V without invalidating their OCZ Lifetime Warranty.