DDR2 has made a fairly weak entry onto the market with underwhelming figures and poor latencies, when we first tested 533mhz on release we found it was no faster than overclocked DDR400 (with very tight latencies). So enter Corsair - one of the leading manufacturers of ram modules who are not resting on their laurels, this time they are bringing into play some exceptionally fast DDR5400 modules, which are rated at 675mhz with a CAS of 4.

The market has been crying out for some 600+mhz modules, to start seeing the benefits of theoretical DDR2 bandwidths. The TWIN2X1024 PC5400 Pro memory is rated at CAS4-4-4-12 and features the famous and flashy active LEDs. This makes Corsairs new PC5400 DDR2 memory 142MHz faster than the original PC4200 DDR2 memory. These TWIN2X1024 PC5400 Pro memory modules come with a life time warranty and are guaranteed to operate at the specified timings and frequencies. When I tested Corsair's original DDR2 modules I was able with the ASUS P5AD2 motherboard to overclock them to 660mhz with timings of 15-5-5-4, so I had high hopes when Corsair sent me these higher revision modules. The new modules are substantially larger than the "first revision" DDR2 boards, and as you can see from the shots (in comparison to older modules) below they come with some very attractive heatspreaders.

While DDR2 is similar to DDR memory, there are a number of enhancements. The biggest feature of DDR2 is its 4-bit prefetch, allowing it to read/write four times the amount of data per clock cycle. This feature effectively doubled the data bus speed while keeping the same 64-bit interface that the original DDR memory used. DDR has 184 pins and DDR2 has 240 pins, without treading old ground as most of us know already DDR2 also requires less power.

So with all these high figures, why isnt DDR2 outperforming its older DDR counterpart? Well basically this is all down to latencies of the ram. tight DDR400 memory can operate at 7-2-2 CAS 2 while most 533mhz DDR2 operated at 12-4-4-CAS 4. The looser (higher) latencies have been counterbalancing the effective clock gains.

DDR 675 is the new standard and hopefully will resolve this issue. Now with Corsair you are always assured quality and everyone loves the LED's Corsair use on their pro modules, not only are they practical, visually depicting load levels but they look gorgeous in a high end system with a window mod, all these "touches" help to justify the high cost. The heatspreaders on these modules are of the highest quality and are thermally affixed to the ICs for optimium thermal transfer, this is a much better solution than the usual double sided tape.

Test setup:

Intel Pentium 4 3.6ghz Engineering sample
Asus P5AD2 Premium
TWIN2X1024 PC5400 Pro
OCZ Powerstream 470watt PSU
Asus Star Ice Cooler
Asus AX800XT
Catalyst 4.11 drivers
Samsung 250gig SATA 16 meg cache HD

Before I start running some benchmarks and quoting figures for the ram, I will delve into the maximum overclocks achieveable. The Asus P5DA2 motherboard incorrectly read the SPD timings as 15-5-5-4 so manual intervention was required to acquire the rated 12-4-4-4, this was rock solid.

Raising the voltage to 1.9 allowed tighter timings of 12-3-4-4 but even up to 2.2 volts nothing higher was possible with this setup. To aid the heatspreaders at higher voltages I used additional cooling with a 120mm fan on a zalman arm attached over the ram. The maximum clocks I could get from the ram at 2 volts was 730mhz @ 12-3-4-4, raising the voltage higher was not a positive experience for the memory, but nonetheless a very good overclock. Lowering latencies to 14-5-5-4, 738mhz was possible but performance was inferior, so im using the 730mhz 12-3-4-4 timings as the reference maximum overclock. I have included DDR533 (stock) scores with DDR 675 (stock) and DDR 730 (overclocked) scores.

An incredible set of results across the board with DDR2 @ 675mhz certainly showing a substantial improvement on bandwidth from 533mhz. Overclocked states give some of the highest results ive seen from any modules to this point, very impressive.

These modules are an overclockers dream especially considering with my test system I was able to hit 730mhz @ 1.9 volts with tighter timings than Corsair have rated (at 675mhz) and almost 740mhz with slightly relaxed timings.

Stability of these modules is without a doubt the highest ive seen, I worked these sticks harder than ive worked any modules and I had not a single lock out, BSOD or random reboot during days of solid stress testing. Not only do these boards finally give DDR2 the much needed boost to outperform DDR, but every attention to detail has been given from the top quality heatspreaders to the compatibility with the three Slot775 boards during testing outside this review.

I really cant recommend Corsair Twin2X1024 PC5400 Pro highly enough, if you are moving to the intel PCI express platform and need the fastest, highest quality DDR2, then there is no competition, these are without a doubt worth every penny.

Available in the UK in many stores such as Overclockers UK for around £265 inc VAT.


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