Intel Core i7-3960X (Sandy Bridge-E) And X79 Platform Preview

Overclocking Sandy Bridge-E

There is a silver lining, though. Sandy Bridge-E is expected to be overclockable in ways Sandy Bridge is not.

Two of the three SKUs purportedly planned for launch will be multiplier-unlocked, simplifying overclocking quite a bit. Both of those models should support ratios as high as 57x (just like the Sandy Bridge-based K-series SKUs were), easily taking care of the air-cooling community. The third, Core i7-3820, will get a number of accessible bins on top of the highest Turbo Boost multiplier, similar to Core i5-2500 and Core i7-2600.

But whereas P67 and Z68 employed internal clock generators, X79’s BCLK comes from a CK505 embedded clock fed through a buffer (a chip that follows Intel’s DB1200GS Differential Buffer Specification) responsible for “gearing” the frequency.

With Sandy Bridge, if you didn’t have an unlocked K-series SKU, or a partially unlocked Core i5/i7, then you were pretty much stuck. Changing the BCLK frequency directly affected other buses, quickly affecting stability. We’ve been able to push single-digit increases, but anything more than 9 or 10 MHz is asking for trouble. Of course, Intel's intention there wasn't nefarious. By integrating the clock, it cut power use and cost on the 25 and 14 MHz crystals. Inflexible scaling just turned out to be a side-effect.

Sandy Bridge-E should alleviate this somewhat by using the buffer chip to apply one of three different ratios to the BCLK. These will modify the PCI Express bus and DMI, creating a greater range of viable frequency settings. I emphasize the word should because I wasn’t able to get the mechanism working on our lab system. Increasing the BCLK and dropping our -3960X’s multiplier simply kept the platform from POSTing, no matter what combination of settings I used.

At least at first, the question to answer is going to be: who cares, anyway? When you consider the Core i7-2600K is completely multiplier-unlocked, who is going to want to fight a partially-unlocked quad-core -3820 on an expensive new X79-based motherboard? The extra 2 MB of L3 cache, two additional memory channels, and PCI Express-rich processor probably won’t inspire many upgrades. The real candidates for greatness are the six-core models, both of which Intel thankfully leaves unlocked. Specifically, I’m excited to see what the Core i7-3930K can do.

Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
  • tri force
    "AMD FX-8150 (Zambezi) 3.6 G...Alright, that's just mean"

    I felt really happy for a second :(
  • xyster
    awesome! thx 4 the preview chris. i've been looking forward to this
  • wicko
    Just bought a 2600k, and after reading this I have no regrets.
  • for the price, the 8150 at 250 dollars will smoke intel out the water. IF you really want to go dolla per dollar , a dual socket amd opteron 6220 system will severely outperform the intel i73960 for alot cheaper. Thats 16 x 3.5 ghz turbo bulldozer cores against 6 3.3 ghz sandy bridge cores. hmm
  • jprahman
    I was really looking forward to Sandy Bridge-E, but it looks like a mixed bag from the review. The lack of USB 3 and especially PCI-E 3 was really disappointing, especially for an enthusiast class processor and chipset. The dearth of SATA ports was pretty surprising too, everything up to this review had indicated far more.

    The extra performance you can get looks pretty nice for stuff like transcoding, but the performance in the majority of applications doesn't justify the extra cost for the i7-3960. I'd rather get a i7-2600K or i5-2500K... or wait for Bulldozer to see how it performs relative to an i5-2500k or i7-2600k.

    To be honest, this review almost comes off like an attempt to chill any interest high-end enthusiasts might have for Bulldozer.
  • hmp_goose
    I predict a "meh" from enthusiast … And a far number of LGA1366 drivers looking for a price cut. ;-)
  • Wamphryi
    I just got an i7 2600 K and like a previous writer commented I have no regrets either. The 2600 K is such good bang for buck and lots of people seem to be snapping them up.
  • Tamz_msc
    I hope Bulldozer is more interesting than this. I honestly dont see many enthusiasts investing in this - they're better off waiting for Ivy Bridge.
  • raclimja
    what a massive disappointment, i was hoping for big performance improvement from intel

    i guess i will just stick with my i5 2500k and upgrade my aging HD 4870 x2 to something like GTX 680 or HD 7900
  • dalauder
    You say the i7-3820 will be a tough sell, but maybe, like the i7-2600, it will be an excellent non-overclocked part for OEM machines. For that purpose, I think a machine that can run DDR3 1600MHz at without overclocking is a reasonable upgrade over the i7-2600.

    There is a market for people who want top-end gaming machines but never want to look inside other than to add more graphics. Based off of Cyberpower, IBuyPower, Alienware, etc.--I bet that market is at least as big as enthusiasts that hand pick their parts.