Verdict: Huge memory bandwidth doesn't deliver performance benefits in Core 2 Duo or Athlon 64 PCs, so the benefit of Corsair's 1,111MHz RAM is limited, especially considering its terrifying £470 price tag. There's simply no way these modules are worth this amount of money, although kudos goes to Corsair for producing some of the most overclockable RAM we've seen.
Our first sight of Corsair's distinctive Dominator RAM modules was in the DDR2 memory Labs test (see Issue 38, p85). 'We'd like to see the Dominator fitted to a faster and more overclockable set of DIMMs before we can thoroughly recommend it,' was James' verdict. Three months later, and his wish may well have been granted. This new 2GB kit is rated at PC2-8888 (1,111MHz), the fastest-rated modules we've seen. It also has lower latency settings than the kit we saw in the Labs test - 4-4-4-12 at 2T. It also supports SLI memory (also known as EPP) for easy overclocking in nForce 590 and 680 boards.
To hit PC2-8888 speeds, the modules' default voltage is 2.4V. This is sizzling - DDR2's reference voltage is 1.8V - so, to keep the Dominators cool, Corsair includes a fan unit called the Dominator Airflow. It's a metal bracket with three 40mm fans that clips over the pair of modules. Like previous Dominators, the PC2-8888 modules have the jargon-tastic DHX technology, Dual-Path Heat Xchange. RAM heatspreaders are usually attached to the memory chips themselves, but this isn't the most effective way of removing heat. So, in addition to touching the chips' casing, the Dominators' large extruded aluminium heatsinks are connected to the all-metal path that connects the RAM chips to the module's grounding plane, which has very high thermal conductivity.
It works too; DHX and the Dominator Airflow keep the modules exceptionally cool. Even with 2.4V coursing through their veins, they remained cold to the touch throughout testing, although the three 40mm fans are noisy.
We planned to test the Dominators using both a Socket AM2 board, the Asus Crosshair, and an LGA775 board, the Asus P5B Deluxe. However, the Dominators are essentially wasted on AM2 systems, as all the boards we've seen lack support for running RAM at speeds higher than DDR2-800. This means that just to get the Dominators to 1,111MHz, you'll need to overclock the FSB to a high setting. The highest FSB of which the Crosshair is capable is 360MHz, which should be enough to test the Dominators, but, at this FSB, with the CPU multiplier set to 5x, the board refused to run the RAM at anything higher than1,080MHz. The P5B Deluxe fared better, as it can run memory at 1,066MHz before you even overclock the FSB. With the Dominator modules set to run at this speed, our test PC scored 1.87 in the image editing test, as opposed to 1.85 with 889MHz memory (the highest speed at which PC2-8000 memory will run in the P5B Deluxe without overclocking). However, 1,066MHz memory made no difference to our test results in F.E.A.R. or Super PI compared to 889MHz RAM.
Sticking with the P5B Deluxe, we overclocked our test CPU - a Core 2 Duo E6700 - by pushing the FSB from 266MHz to 278MHz, which ran the Dominators at 1,111MHz. However, despite many hours of tweaking, we couldn't get the modules to run much faster than this. The P5B's problem is that the maximum DDR2 voltage it allows is 2.45V, which is barely above the Dominators' reference voltage. This allowed us to push the FSB to 288MHz, running the memory at 1,152MHz, which is fast, but not as quick as the Labs-winning A-Data Vitesta DDR2 1000+, which hit 1,180MHz.
Undeterred, we next tried the Dominators in the Asus Striker Extreme (see p38), an Nvidia nForce 680i motherboard. Engaging SLI memory pushed the modules to 1,111MHz, although the latencies changed to 4-5-5-12. Sadly, we couldn't significantly improve on this speed, even when we tried overclocking in the BIOS. Despite the fact that the Striker Extreme can zap DDR2 with up to 3.425V, the Dominators refused to budge above 1,132MHz, and slackening the timings made no difference either. Finally, we turned to BFG's new nForce 680i board, which we'll be reviewing next issue. The Dominators appreciated this, running stably at 1,280MHz and happily posting at a ludicrous 1,333MHz, although the test system wasn't stable at this speed, most likely because the board can only send 2.5V to the memory. This is still the highest memory frequency we've seen, although other modules, including Corsair's own standard PC2-8500 RAM, also managed this speed in the BFG.
