Test Setup

Test System
CPU:	Intel E6300 Conroe 1.8 GHz, 2 MB Cache
Motherboard:	ASUS P5B Deluxe BIOS 1101 Intel P965 C1
Video Card:	ATI Radeon X850 Pro PCI-E
Harddisk:	Maxtor DiamondMax 160GB
Power Supply:	OCZ GameXStream 700W
Software:	Windows XP SP2, Catalyst 7.6

Performance

In the first test we evaluate how these modules do at their default settings of 4-4-3-10, to establish a baseline performance value. At those settings we increased the clocks as far as possible to find out how much overclocking you can get out of the box.
The next three tests show how well the memory responds to different voltages at the CL5 setting. The frequencies shown are the maximum stable clock at this setting. As you can see the overclocks scale very nicely, the more juice you give the memory. The same is happening for the CL4 and CL3 scenarios. Please note that we had to run the CL3 tests at 3-3-3-4 because 3-2-2-4 was extremely unstable, the memory only booted with 2.25V+.
I find it very important to point out that the memory can run DDR2-800 MHz @ CL4 at 1.8Vand that you can reach DDR2-1066 @ CL5 with about 2.30V. With a bit of tweaking you can probably get it to run DDR2-800 @ CL3 but it will require a lot of voltage.
These different timings gives you added flexibility in situations where you want to reduce the clocks a bit and tighten the timings.

After looking through the benchmarks you can see that maximizing CPU clock is the most important factor when it comes to performance, then you should optimize memory speed.

Mushkin XP2-6400 2 GB Kit
CPU Clock & Memory Ratio	Memory Speed	Memory Timings	Everest Read	Everest Write	Everest Latency	Quake 3 Timedemo	3DMark 2001SE	SuperPi Mod 1M
6 x 266 2:3	400 MHz	4-4-3-10 2.1V	6250 MB/s	4219 MB/s	75.4 ns	472.4 fps	23457	33.30 s
6 x 293 1:2	439 MHz	4-4-3-10 2.1V	6879 MB/s	4641 MB/s	68.7 ns	518.7 fps	25400	30.27 s
6 x 336 2:3	504 MHz	5-5-5-15 1.85V	7877 MB/s	5333 MB/s	61.5 ns	589.1 fps	27986	26.42 s
6 x 354 2:3	531 MHz	5-5-5-15 2.15V	8304 MB/s	5624 MB/s	58.3 ns	621.6 fps	29201	25.08 s
6 x 379 2:3	568 MHz	5-5-5-15 2.35V	8881 MB/s	6014 MB/s	54.5 ns	662.1 fps	30060	23.49 s
6 x 276 2:3	414 MHz	4-4-4-12 1.85V	6478 MB/s	4376 MB/s	72.9 ns	331.6 fps	24174	32.13 s
6 x 319 2:3	479 MHz	4-4-4-12 2.15V	7507 MB/s	5062 MB/s	63.0 ns	382.9 fps	27246	27.77 s
6 x 344 2:3	516 MHz	4-4-4-12 2.35V	8074 MB/s	5462 MB/s	58.6 ns	411.8 fps	28645	25.73 s
6 x 255 4:5	319 MHz	3-3-3-4 1.85V	5585 MB/s	4027 MB/s	88.7 ns	436.0 fps	21630	35.49 s
6 x 293 4:5	366 MHz	3-3-3-4 2.15V	6423 MB/s	4631 MB/s	77.1 ns	496.5 fps	24238	30.91 s
6 x 319 4:5	399 MHz	3-3-3-4 2.35V	7017 MB/s	5043 MB/s	70.9 ns	541.2 fps	25918	28.40 s

This graph shows you at a quick glance which clock frequencies you can expect at which voltage. Please note that each individual module overclocks different, the results here can only be seen as an indicator of performance.