Kingston's KHX6400D2LLK2/2G is a kit of two low-latency 128M x 64-bit 1GB (1024MB) DDR2-800 CL4 SDRAM (Synchronous DRAM) memory modules, based on sixteen 64M x 8-bit DDR2 FBGA components per module. Total kit capacity is 2GB 2048MB). Each module pair has been tested to run at DDR2 800MHz at low latency timing of 4-4-4-12 at 2.0V. The SPD is programmed to JEDEC standard latency 667Mhz timing of 5-5-5-15 at 1.8V. Each 240-pin DIMM uses gold contact fingers and requires +1.8V.
Kingston's HyperX modules ship in a slim, sturdy plastic protector, which is quite a bit smaller and less flashy in comparison to other enthusiast targeted memory modules. Kingston lets you directly see the module information from the outside of the package before you purchase, although besides the model number and recommended voltage level (1.95V), we are not able to decode any useful information.
Interestingly enough, a cursory glance at Kingston's website and PDF files for these specific memory modules actually differ from what is stated directly on the memory module. While Kingston states a 1.95V voltage level, their PDF file states the following recommended timings and voltages.
That's odd. Luckily there is not too much variance between 1.95V and 2.0V, so if your motherboard supports it, we would say just go ahead and stick with 2.0V to be safe.
The recommended latencies of CAS 4-4-4-12 at 800 MHz clock speeds are very good, as the vast majority of "standard" DDR2-800 memory modules on the market run at CAS 5-5-5-18 latencies at this same clock speed. Our testing in the past has shown that CAS 4-4-4 latencies typically deliver about 5% better overall system performance across the board compared to CAS 5-5-5 modules. Kingston's HyperX modules can run at these timings without any overclocking, so we're looking at a nice performance upgrade with zero stability risk here by using these KHX modules over generic ones.
These particular Kingston HyperX modules do not support EPP (Enhanced Performance Profiles), although at the time of writing, Kingston is now producing EPP-compatible variants of these modules. EPP will auto-adjust the memory timings to the manufacturer's specific high-end settings on EPP-enabled motherboards. Since these modules do not support this technology, clock speeds and timings have to be set manually in the motherboard's BIOS. If manual timings are not set, the motherboard will fall back on SPD (Serial Presence Detect) defaults, which in the case of this particular module are DDR2-667 clock speeds with CAS 5-5-5-15 latencies @ 1.8V. Obviously, running these modules at SPD defaults would very much be a waste, so manual timing of these modules is a necessity.
In standard Kingston HyperX fashion, these modules are equipped with dodger blue anodized aluminum alloy heat spreaders which are bolted (more or less) to the memory chips by a set of high-pressure metal clips. The heat spreaders have proved themselves to be effective in the past, so we have no reason to doubt their abilities now. Underneath the heatsinks, if you choose to pry them off (we'll do it, so you don't have to), lie Elpida-branded memory chips. Our chips were labeled as Elpida's E5108AG-6E-E, which are officially rated as DDR2-667 CAS 5-5-5 chips from Elpida, according to their PDF sheet. Despite the chip rating, the module had no issues running at Kingston's promised CAS 4-4-4 latencies at 800 MHz clock speeds.