Intel Core i7-975 Extreme And i7-950 Reviewed

Overclocking/Memory Scaling

We wanted to test Intel’s Core i7-975 Extreme in two different ways: processor overclocking and memory scaling.

The first part was easy, especially with an Extreme CPU. We used quick multiplier adjustments and found that 31x (4.12 GHz) was as fast as we could go stably. With voltages up to 1.385 V, we were able to get into Windows at 4.25 GHz, but at that point, it only takes a couple of minutes under Prime95 to push you into the 92-93 degree Celsius range, where blue screens are inevitable (this is with Thermalright’s Ultra 120 Extreme—naturally, the situation changes as you pursue more aggressive cooling). 

Once we backed off of 4.25 GHz, we were able to drop the voltage required for stability at 4.12 GHz all the way to 1.29 V. In order to switch things up a little bit, we also dropped the multiplier to 23x and hit 4.14 GHz with a 180 MHz Bclk (20 x anything over 200 MHz simply wasn’t cooperative). In either case, the result of our encoding test was exactly the same (1:05). Use multipliers if you can or Bclk if you’re not running an Extreme chip—what matters is that you hit your target.

Although the Core i7-975 Extreme sports the same 130W TDP as its predecessor, it's interesting that the new CPU runs a higher voltage by default (and despite the fact that it's a D0 stepping). See the CPU-Z screenshots up top for more.

OCZ was also kind enough to send over a set of its DDR3 PC3-17000 Blade modules specified for DDR3-2133 at 8-9-8. Given the extreme variance in price between mainstream and high-end DDR3 memory, we thought it’d be a good idea to quickly explore the benefits of loading up on memory running at those extreme speeds. In theory, low latencies are best in environments heavy on multi-tasking, where the fast timings enable quick bursts. Conversely, you’d suspect gobs of bandwidth to help most in data-intensive apps like video encode jobs.

It's worth noting, too, that achieving DDR3-2133 speeds necessitated bumping our QPI voltage to 1.75V (a substantial increase). This was required in order to run the cache/uncore at 4,266 MHz (twice memory speed). Even then, we were able to take a memory bandwidth reading but not complete a full run of MainConcept without stability issues. This is something that'll inevitably get worked out over time, we're sure. For now, OCZ considers the ICs that bin for these speeds to be the top 1% or so.

As you can see, there’s a huge difference in the bandwidth we’re moving using this triple-channel kit. The only truly strange result came from running at DDR3-800, where the memory controller switched off one channel, resulting in the lower-throughput result. Otherwise, the step-down is fairly even, so long as you maintain timings.

This is all well and good, of course, if you have modules able to do, say, DDR3-1066 at 5-4-4. But what if you want to compare an older DDR3-1066 kit running 9-9-9 to a lower-latency upgrade? We ran those numbers too, just to check, and came up with 19 GB/s (compared to 20.4 GB/s at 5-4-4).

For the most part, our real-world encoding batch demonstrates zero impact each step of the way. And even when we run the DDR3-1066/9-9-9 configuration, we come back with 1:19 as a result. At least in your average desktop environment, Intel’s Core i7 does not seem to be starved for throughput. We’ll spend some time exploring what exactly it does take to tax the micro-architecture’s memory subsystem in a couple of weeks.

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  • mi1ez
    "If you spend enough time in our comments section, then you’re probably under the impression that AMD currently holds the performance crown and can do no wrong. I get it; AMD is the underdog and it’s hip to applaud competition. I'm certainly in favor of faster hardware, lower prices, and fair capitalism; those things benefit us all.

    But don’t let the fanboys fool you—Intel’s Core i7 is the fastest CPU out there, which is why, even after giving our readers a chance to weigh in and guide the direction of our System Builder Marathon series, two of the three builds ended up based on Core i7-920 CPUs."

    What comments sections have you been reading?! Everything I've read give pretty much even credit to Intel and AMD.
  • mi1ez
    "I don’t have any problem recommending Core i7 over Phenom II right now—even if it costs an extra $100"

    And you bemoan the AMD fanboys?

    It's a question of the situation you find yourself in.
  • LePhuronn
    I'm still waiting for the review that explicitly states the advantage running QPI at 6.4GT/s has over 4.2GT/s - that's the only thing in my mind about the worth of an EE over a standard chip.

    If a faster QPI has real-world benefits then there's still a reason to consider an EE, even though (unlocked multipliers or not) the silicon seems unable in most cases to go much past 4.2GHz (hence the 920 dumping over everything other i7).

    With all the talk about the 920 being phased out, I'd like to see some 950-based overclocking to see if she can do the same - Intel can dump the cheaper chips to maintain the EE's supposed dominance, but if a 950 can do what the 920 did then it's an exercise in futility.

    Looks like I better get my 920 now before they vanish!
  • LePhuronn
    "Of course, if you’re running a retail should be able to manually tune QPI speed up to 6.4 GT/s in your motherboard’s BIOS"

    You can do that? Is there any reason to get an EE at all then? The 920 can outclock the 965 and 975 and the QPI can bump up to EE levels in the BIOS all for about a grand less!
  • papalarge123
    from what i have seen in all of the benchies from the past 6+ months, is that if u have an overclocked Core 2 Quad @ 3.6+, and u are mainly using the system for gaming, then i can not see the reason to upgrade to the i7 at this precise moment.

    i agree that if u r due an upgrade from an old x2 on an obsolete 939 board or an intel 775 board that doesnt support quads, then the i7 is a tasty bit of kit, but if u have an am2+ board or even an intel board that can take the latest quads in the core 2 range and mainly play games, then the i7 is a waste of money no matter how cheap and powerfull the lowest 920 is.
  • LePhuronn

    There's more to PCs than gaming, and that's where the attractiveness of the i7 is right now. Yes, if you're gaming then no need to spend the money, although I'd like to see some comparisons between a C2Q and i7 running quad-aware games like GTAIV.

    Media and production-wise the i7 will pound anything. A colleague of mine just built a 920 OCed to 3.8GHz with 12GB RAM and a Quadro CX and DEAR GOD Adobe CS4 runs like a wet dream.
  • jwoollis
    Please publish the exact details on how to overclock each CPU on any available motherboard so that we can attempt to replicate these tests for ourselves
  • Anonymous
    eh can someone tell me wat is aa and af and how to turn them on
  • Reynod
    You can't spin this anyway other than down.

    It is a hugely overpriced and underperforming dog of a chip that has to be cooked a few millivolts higher just to run under load.

    It runs hotter (at idle and under load), and actually performs less than a 965 under most benchmarks.

    Why ??

    I think it is lower quality silicon that has been repackaged so that Intel can extract the maximum bang for the buck - it might be D0 but it is certainly not the best silicon ... or it would run at comparable or lower voltage than the 965.

    A wise purchase for an gamer would be to get a core2quad or phenom II, or possibly an i7920 and overclock them.

    Only an idiot would buy a 975.

    Check the other reviews.

    Obviously i7 does not scale as well as core2 or Phenom II ... certainly the case for gaming.

    130 Watts my ar$e ... more like 140 Watts.

    Shame on you Spintel for thinking you can rip us off !!
  • Anonymous
    Surely if you're testing CPU's for gaming you want the most powerful graphics card possible, so as to avoid the very graphics bottlenecks that show up in your games tests. I appreciate a 4870 X2 probably would have handed an advantage to the i7's, but anyone who is buying an "extreme" processor probably isn't short of money to burn.
  • Anonymous
    WTF Over at Firingsquad the Core I7 smokes all CPU's in FarCry2...but over here it loses? Who the hell buys a $1000 CPU and pairs it with a Nvidia Geforce 260? Come on use it with at least the 295!!
  • wild9
    My God, look at the price differences between the i7 and Phenom II..the i7 may have a comfortable lead in core performance but value?? Hmm.
  • wild9
    Then again, consider that the cheapest Intel chip represented here, the i7-920, is still $30 more expensive than AMD’s flagship.

    Motherboards and RAM would significantly add to that difference.
  • wild9
    For buying new that i-720 looks very attractive (yep, I commended Intel!). But do most people want to spend that much?

    This is the difference between AMD and Intel; you need a whole new board, new memory just to run the i7, so the initial outlay is misleading. Conversely, if you're sitting there with a dual-core AMD and want some more punch then you just update your BIOS, drop the Phenom II in and away you go. The case against the i7 becomes even stronger when one considers that most people just use their machines for basic tasks. Most of the clients I build PC's for want upgrades or low-cost/high-performance HTPC systems. They just won't pay for the overheads associated with going the i7 route..
  • AGTDenton
    I made the biggest mistake buying into the Phenoms. Wish I could turn back the clock. I've had 3 so far and each one has been a dissappointment. Wont be buying another Phenom and wont be buying another AMD based system for an extremely long time, they have really P'd me off. The Spider and Dragon platforms are a waste of time.
  • wild9
    Which particular model(s) did you purchase?
  • Anonymous
    I cannot believe someone can buy 3 Phenons, seriously you need to step back here and stop expecting 12 months of processor progress to deliver a totally new experience. Its the same with graphics cards too, just because a card is 20% faster doesn't mean that its worth scrapping your old one just to get it, you'll be hard pressed most days just to notice that level of performance.

    Got to admit I seem to be a bit of a AMD fanboi these days, although even then I'm amazed by the performance of the I7 for productivity stuff, Intel do have a scary lead there. In games though I'd just not bother with it (only Everquest2 I know of uses the CPU heavily and even that is changing) since a good graphics card makes way more difference. Hence I'm picking a PhenonII 955 (actually overkill, but what the heck), a stop gap 4870 graphics card (until DX11 comes out) and going to sit back and enjoy.
  • krenar41
    core i7 are expensive and not necessary.AMD platforms are the best cheap and fast enough