Uncovering
Please excuse the low-quality shot. Getting the adhesive remnants off proved to be impossible. Careful reading of the ICs showed the modules to be manufactured by Samsung, with K4H560838F-TCCD codes. What's suprising is that this is 4ns (DDR500) memory with default latency parameters of 3-4-4-8. Corsair's used a custom PCB to tweak the timings for ultra-low latencies at DDR400 speeds. It's not just a case of, as many see it, using faster memory at lower latencies. Try running general DDR500 memory at 2-2-2-5 (DDR400). The overwhelming number of modules will simply fail to boot. Aggressive latency tweaking, however, can also result in ICs not hitting their default specification, which is PC4000 here.
Whether the LEDs are a value-adding extra or a waste of money is a purely personal judgment. Corsair also markets similar memory that does without the fancy heatspreader and LEDs but which carries the same basic spec. for a few £s less.
Official specifications
512MB and 1024MB kits available
Implemented using 16 256MBit chips per module (1GB kit)
Samusng DDR500 3-4-4 RAM on a custom Corsair PCB
95% greater surface area than standard memory heatspreaders
18 LEDs show the level of memory activity
100% tested at 200MHz (DDR500)
Lifetime Corsair warranty
Plug-n-Frag Auto-Configuration
Latency: 2-2-2-5-1T @ 2.75v
It's a shame that Corsair couldn't implement 2-2-2-5 timings at 2.5-2.6v. We guess that's a bridge too far.