Memory Scaling on Core i7 - Is DDR3-1066 Really the Best Choice?

Memory Pricing

We remember paying over $600 for 2GB of DDR3-1600 C7 rated at 1.90V almost two years ago. About nine months ago, when Core i7 launched a DDR3-1600 C7 6GB 1.65V kit cost us $415. A DDR3-1600 C7 1.65V 6GB kit cost us $140 last week. To add insult to injury, a recently purchased DDR3-1600 C9 1.65V 6GB kit set us back $86 compared to the $195 we paid four months ago. To say things have changed in the DDR3 memory market over the past two years would be an understatement.

In today’s testing, we did our best to utilize retail kits from various manufacturers based on their stock speed and timing ratings for each of our memory settings. We felt this was a better choice than taking a DDR3-2000 kit and using it at different speeds and timings as that would not represent what the actual product for sale at these price points are capable of in our test system. Of course, we violated this principal twice but for good reason. There are not any 1066 C5 kits so we bumped the voltage slightly on the Patriot 1066 C7 kit to run at these timings. Our 1866 C7 kit became incapacitated and we switched to a 2000 C8 kit that actually cost less and performed better.

The price levels listed represent our cost from Newegg at the time of purchase. Of course, prices for 6GB kits vary widely depending on the manufacturer, rebates, specifications, and product availability so consider these prices to represent a current aggregate average. We fully realize that purchasing a DDR3-2000 CAS8 kit for $235 that is capable of running DDR3-1866 C7 at like voltages is usually a better value than a $289 1866 C7 kit. Kit prices range from $80 for the DDR3-1066 C7 kit up to the $260 DDR3-2000 C8 modules for this article.

Our lead off contestant is the Patriot DDR3-1066 C7 PSD36G1066KH 6GB kit that we utilized for both the 1066 C7 and C5 results. This memory kit only required 1.60V for CAS5 operation and comes in at the low price of $80. For those operating on a strict budget, we cannot say enough good things about this kit as it easily reached DDR3-1600 C9 on 1.65V and 1.225V VTT. Speaking of DDR3-1600 C9 kits, we are now seeing these 6GB kits below $90 and if they arrive with the right IC/PCB combination, they could potentially make a great kit for down clocking to 1333 C6, which is one of our sweet spot settings for overall performance on this platform.

We tapped Corsair for our DDR3-1333 C9 kit, SuperTalent for the DDR3-1333 C8 modules, and GEIL for our DDR3-1333 C7/C6 kits. We turned to Patriot once again for DDR3-1600 C9, OCZ for a really great DDR3-1600 C8 setup, Corsair for DDR3-1600 C7, and Mushkin for one sweet DDR3-1600 C6 package. We utilized GSkill’s DDR3-2000 C8 kit for our DDR3-1866 C7 and limited overclock results. We will be reviewing each kit utilized shortly (and others) to determine the overall best value based on clocking abilities, technical support, warranty, and cost.

Memory Designations –

One of the more confusing aspects of selecting DDR3 memory are the two common designations, which are both technically wrong. The first commonly used term describes the theoretical bandwidth, as in PC16000. This numbering system represents the peak transfer rate in MB/s of the module. The other common designation describes the effective clock speed in terms like 2000MHz. If the product description does not contain the effective clock speed and you only see a number like PC8500, then divide it by eight. Therefore, through the magic of math and marketing, PC8500 becomes 1066MHz.

Of course, this is not the actual clock speed, but rather the data rate. In other words, while PC8500 sounds extremely impressive and 1066MHz just a little less so, the actual operating frequency of the DDR3 devices is much less. There is a history on why we have these inflated numbers as it dates back to the time of RAMBUS, but that is a story for another article. We just wish that the memory suppliers would pick one designation and go with it. In the meantime, we will report our numbers today in effective data rate for simplicity state. We will refer to DDR3-1066 5-5-5-18 as simply 1066 C5 as an example.