Investigating Sandy Bridge Memory Scaling

Intel's Second Generation Core processors, based on the Sandy Bridge architecture, include a number of improvements over the previous generation's Nehalem architecture. We’ll be testing one specific area today: the improved memory controller. Current Sandy Bridge based processors officially support up to DDR3-1333 memory. Unfortunately, due to changes in the architecture, using faster rated memory (or overclocking memory) on Sandy Bridge via raising the base clock is extremely limited. Luckily, there are additional memory multipliers that support DDR3-1600, DDR3-1866, and DDR3-2133 memory. Some motherboards include support for even higher memory multipliers, but we’ll confine our investigations to DDR3-2133 and below.

Since Sandy Bridge is rated for up to DDR3-1333 memory, we will start there and work our way up to DDR3-2133 memory. We'll also be testing a variety of common CAS latency options for these memory speeds. Our purpose is to show how higher bandwidth memory affects performance on Sandy Bridge, and how latency changes—or doesn’t change—the picture. More specifically, we’ll be looking at the impact of memory speed on application and gaming performance, with some synthetic memory tests thrown into the mix. We’ll also test some overclocked configurations. So how much difference will lowering the CAS latency make, and does memory performance scale with processor clock speed?

Back when I originally envisioned this comparison, the price gap between DDR3-1333 and DDR3-2133 memory was much wider. A quick scan of Newegg reveals that a mere $34 separates those two 4GB kits. Below is a breakdown of the lowest prices (as of 7/16/2011) for various memory configurations.

4GB 2x2GB Kits
DDR3-1333 CL9 $31
DDR3-1333 CL8 $40
DDR3-1600 CL9 $40
DDR3-1600 CL8 $41
DDR3-1333 CL7 $45
DDR3-1600 CL7 $50
DDR3-1866 CL9 $60
DDR3-2133 CL9 $65


8GB 2x4GB Kits
DDR3-1333 CL9 $58
DDR3-1600 CL9 $66
DDR3-1333 CL7 $75
DDR3-1600 CL8 $80
DDR3-1866 CL9 $85
DDR3-1600 CL7 $115
DDR3-2133 CL9 $150

You can see from the above chart that balancing memory clocks with latency results in some interesting choices, particularly on the 8GB kits where price differences are a bit larger. Is it best to go with a slower clock speed and better timings, or vice versa, or is the optimal path somewhere in between? That’s the aim of this article.

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  • Rick83 - Monday, July 25, 2011 - link

    Fancy heat spreaders are the worst that has ever happened to RAM.

    It gets worse when you have to pay more to get rid of it, as with the new low profile vengeance series from corsair.

    Memory doesn't usually get that hot anyway, and the large heat spreaders impede airflow between the modules in fully populated setups, as well as limit what size your cooler can be, occasionally forcing you to get one of those water-cooler-in-a-box things which incur massive extra costs.

    The only reason I don't want to have completely naked memory, is that the heat spreader gives the RAM some ESD protection, which is actually useful.
    Reply
  • JoJoman88 - Monday, July 25, 2011 - link

    The review just made your post the truest of them all jabber! Reply
  • Spacecomber - Monday, July 25, 2011 - link

    In the past, one reason to get faster rated memory is that you eventually would see a migration of what was the standard memory module to something running on a faster bus speed. I'm not sure if that really holds true, anymore. It seems that these days you are more likely to see the adoption of a completely new type of memory, rather than an existing standard sticking around long enough for the minimum required memory speeds it is based on to go up. Reply
  • geofelt - Monday, July 25, 2011 - link

    One of the price differentiators is the heat spreaders.
    Apart from the aesthetics, where is the value of fancy heat spreaders? Can it be measured?
    Seems to me that they are mostly marketing gimmicks, excepting perhaps for those used on overclocking competitions.
    I would like to see some sort of a study to determine the value of heat spreaders.
    Reply
  • MrSpadge - Wednesday, July 27, 2011 - link

    Short answer: nothing.

    MrS
    Reply
  • BobDavid - Monday, July 25, 2011 - link

    see subject Reply
  • JarredWalton - Monday, July 25, 2011 - link

    See the conclusion; we already did a look at that (with HD 3000 and Llano).
    http://www.anandtech.com/show/4476/amd-a83850-revi...
    Reply
  • LoneWolf15 - Monday, July 25, 2011 - link

    Ivy Bridge will be out next year. There is a reasonable chance it could have a bump in memory bandwidth. Buy RAM at one or two multipliers above what you need now, and when the upgrade comes along, you won't be wishing for new RAM.

    DDR3 is so cheap right now, it's worth planning ahead.
    Reply
  • dman - Monday, July 25, 2011 - link

    I've been looking for a review like this for a while, was a good read even if it didn't come as a huge surprise. I'm definitely interested in the AMD platform results if/when those are available. Reply
  • SteveSweetz - Monday, July 25, 2011 - link

    I was disappointed to see this article lacked the detail (and quantity) of the gaming tests versus it's predecessor on AnandTech: http://www.anandtech.com/show/2792/10

    That article showed that memory frequency and latency changes had a greater impact in some games than others, and that in most cases the memory also had a greater impact on the minimum framerate (an important consideration) than average framerate.

    Also disappointing to see no CAS6 sticks tested here. Particularly because 2GB 1600MHz CAS6 were relatively common at one point, but now, for whatever reason, G.Skill is the only company that still makes them. It'd be interesting to see if that's a meaningful exclusive. The previous article showed CAS latency being more important than frequency in some cases.
    Reply

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