Corsair XMS2 8500
First on our list is Corsair's XMS2 2GB DDR-2 modules set for a base line speed of 1066MHz DDR. These modules are set to be the companion to the Intel Core 2 systems using a 266MHz FSB, as these modules will run 1:2 at 533MHz (1066MHz) without a problem. These also will work well with AMD Athlon 64 systems as 266MHz FSB on AMD is nothing these days.
Corsair's XMS2 modules look quite identical to any of the other modules they have released to the market in the XMS range. The "2" on the end identifies that these are DDR-2 modules, so you won't buy DDR accidentally for your DDR-2 system or vice versa. The black heatspreader is prominent in the Corsair range with a white and purple sticker on the front and back.
On the front side of the modules is where Corsair put some basic info on the modules which includes operating speeds, speed rating of the memory and the serial number.
Our kit was a 2GB DDR-2 XMS2 8500 series with timings of 5-5-5-15-2T running at 1.8v. These modules have been rated with the new EPP or Enhanced Performance Profile of 5-5-12-2T with a maximum voltage rating of 2.2v for 1066MHz DDR if you want to push your RAM that hard.
We kept the speeds at the SPD defaults to give us the best possible overclocking curve. We managed to get a maximum speed of 1308MHz DDR (654MHz) total out of the memory using SPD timings and voltage of 2.2v. We did try higher voltage to the extent of 2.5v but this simply didn't allow any faster speed - in fact, it resulted in instabilities at 1308MHz DDR.
Next on the list is G.Skill's 1000MHz DDR-2 modules. These modules use a standard bus speed of 500MHz to obtain their DDR-2 1000MHz rating and are ideal for AMD processors and the new Core 2 range from Intel with 266MHz FSB.
G.Skill's modules are a matched pair of 1GB modules for a 2GB kit and 512MB modules for the 1GB kit. We received the 2GB kit for our testings. The heatspreader is a black thin alloy heatspreader with G.Skill's logo and name in raised engravings. These are held onto the modules with doubled sided heat transfer tape and 2 U-clamps at both ends.
On the front side of the module is a sticker with the memory timing ratings as well as the serial number. G.Skill have set the timings at 4-4-4-5-2T (the best timings in any of the 1066MHz DDR memory we tested here today) with a maximum supported voltage of 2.2-2.3v depending on what your motherboard supports. Anything above 2.2-2.3v will void warranty; however, this is more than enough for our testings.
We ran the full 2.3v into the memory and managed a final speed of 1185MHz DDR (592.5MHz) fully stable at SPD timings. Users in forums have been reaching speeds over this by reducing the timings but we are only interested in the maximum speed at SPD for this article. While higher clock speed is good, tight SPD timings are also very important.
We did push the voltage to 2.5v but this did not result in any further speed increase - stability was identical to that at 2.3v, so there is no need to run an extra 0.2v into the RAM for no reason but to shorten the life of the modules.