Core 2 Duo: Effects Of Memory Timings

Last week, Intel allowed us to publish independent performance results from its upcoming Core 2 Duo processors that are set to go on sale later this month. Core 2 Duo's performance is nothing short of groundbreaking - it finally allowing Intel to take back the performance crown that AMD has held on to since September 2003 when it unleashed the impressive K8 architecture, making Intel's NetBurst architecture look somewhat dated. The introduction of Core 2 Duo not only made AMD's K8 architecture look a little dated in some areas, it succeeded in making the NetBurst architecture look like something from pre-historic times.

At the end of our Core 2 Duo performance analysis, we mentioned that there were many more caveats of Intel's new Core microarchitecture to look into. One such caveat is the effects of memory timings. Over the course of this article, we're going to cover the bases of memory timings at DDR2-800 using our favoured Core 2 Duo processors: the E6400 and E6600. Both the E6400 and E6600 look to be right in the sweetspot of Intel's line up at £182 and £252 respectively. They also represent both the 2MB and 4MB L2 cache versions of Core 2 Duo too, so it should give you an idea of what to expect from tweaking memory timings on all of the current Core 2 Duo processors.

There are some very good DDR2-800 memory modules out there at the moment with varying timings and hugely varying prices too. Indeed, Corsair is currently the market leader in the world of DDR2 and it ships three different 2GB DDR2-800 kits in its XMS2 enthusiast-orientated line of memory. The difference between the high end and low end parts is over £200 - that's quite a massive difference, but you're paying for the additional qualification and testing that has to be done on the premium XMS2-6400C3 modules.

Along with the 6400C3 part, Corsair offers DDR2-800 modules rated at 4-4-4-12 and 5-5-5-12. If you choose to purchase some of the slower modules, you may not have as much success when it comes to overclocking - that's definitely a reason to consider the 6400C3 modules, as we've found them to be very good overclockers.

Other manufacturers are slowly catching up with Corsair. OCZ recently announced its own DDR2-800 CAS3 part - the PC2-6400 Titanium Alpha XTC Series - which are rated at exactly the same timings as the Corsair XMS2-6400C3 modules. The likes of Crucial, G-Skill and Kingston are still shipping DDR2-800 modules rated at 4.0-4-4-12 - these companys may well be planning to ship lower-latency DDR2-800 parts, but they are currently not shipping.

The question is though - aside from overclocking - do tight memory timings make a fat lot of difference on Intel's Core 2 Duo processors? Another question - which we're sure is on your minds - is it worth paying more for premium memory if you're looking at building a Core 2 Duo-based machine without getting your feet wet in overclocking? We hope to be able to answer these questions over the course of this article.

Test Setup:

ASUS P5W DH Deluxe motherboard (Intel 975X/ICH7R); BFG Tech GeForce 7900 GTX OC video card (operating at 670/1640MHz); Seagate 7200.9 200GB SATA Hard Disk Drive; LG 16x DVD-ROM drive, OCZ GameXStream 700W PSU; Windows XP Professional Service Pack 2; Intel Inf 7.22 WHQL platform drivers; NVIDIA Forceware 91.31 WHQL.

Processors:

• Core 2 Duo E6600 - 2.40GHz, 1066MHz FSB, 4MB L2 cache;
  
• Core 2 Duo E6400 - 2.13GHz, 1066MHz FSB, 2MB L2 cache

Memory & Timings:

• 2x1GB Corsair XMS2-6400C3 running at DDR2-800 with 3.0-3-3-9 timings;
  
• 2x1GB Corsair XMS2-6400C4 running at DDR2-800 with 4.0-4-4-12 timings;
  
• 2x1GB Corsair XMS2-6400PRO running at DDR2-800 with 5.0-5-5-15 timings.

Instead of using Intel's D975XBX motherboard, we have chosen ASUS' all-new P5W DH Deluxe motherboard based on the 975X chipset. Typically, the ASUS motherboards have been faster than the Intel-built motherboards and they offer many more tweaking features for the enthusiast looking to get the most out of their system. The P5W DH Deluxe is no different in that respect and is set up more aggressively than the Intel D975XBX mobo. We will have a full review of the P5W DH Deluxe motherboard in the near future.