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Overcoming Stability Issues At 4.1 GHz

Overclocked On Air: Intel's Core i5-750
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We took the Core i5-750 to 4.1 GHz using a 1.465V BIOS Vcore, but the system would not return from peak performance to idle without crashing. Further voltage modifications on the processor or platform side didn’t help. We were able to continue increasing clock speed after switching off C-states support in the BIOS.

Unfortunately, the system idle power went up by a massive 34W after performing this operation. While it allowed us to reach higher frequencies, this action also emphasizes how important it is to keep the processor in the lowest possible operation state when it's idle, meaning that transistors and entire functional units have to be switched off when they are not needed.

Final Speed: 4.3 GHz

A step up to 1.52V was required to reach 4.2 GHz reliably. 

We reached 4.3 GHz on the Core i5-750 by applying 1.55V core voltage, but this setting wasn’t dependable. It was stable enough to run Fritz and take CPU-Z benchmarks, but we could not complete our entire benchmark suite. However, this setting isn’t something we recommend for everyday operation anyway, as power consumption has increased by 127W over standard settings. Let’s look at the performance levels you can reach through overclocking to as much as 4.2 GHz and how these changes affect efficiency.

Please have a look at our CPU-Z image gallery to look at all the speeds and settings.

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Top Comments
  • 21 Hide
    curnel_D , October 28, 2009 7:42 AM
    cyberkuberiahnice to see a huge boost in productivity/non gaming applications .

    Nice to see a huge boost in gaming/non productive applications as well. :p 
Other Comments
  • 1 Hide
    cyberkuberiah , October 28, 2009 6:46 AM
    nice to see a huge boost in productivity/non gaming applications .
  • 21 Hide
    curnel_D , October 28, 2009 7:42 AM
    cyberkuberiahnice to see a huge boost in productivity/non gaming applications .

    Nice to see a huge boost in gaming/non productive applications as well. :p 
  • 9 Hide
    coconutboy , October 28, 2009 8:03 AM
    Good article guys, the screenshot gallery is great, thanks for that! I'm a modest OCer these days so sub-4GHz overclocks w/ little to no voltage increase is exactly what I'm interested in and the screenies are useful as a reference. Even better, you used one of the 3 main mobos I've been considering.

    Question about the MSI GD65: Patrick/Achim did you guys try using any Channel Well based PSUs and if so did you experience any of the problems Atech mentioned in their review? (scroll down to the 4th paragraph) I recently purchased a Corsair 750hx and have noticed a fair number of comments not only in that linked article but also in places like newegg etc. The OC Genie issue doesn't bother me much but just hearing that there's any sort of problem at all between MSI boards and CWT-based PSUs has me a lil' sketchy till it's (presumably) fixed in a BIOS update. The Anandtech article mentioned they had the exact same problem w/ the GD80 so till MSI sorts their P55 problems out I'm on the fence about going w/ my first choice, the GD65 (LOVE that board's layout), or instead switching to the Asus/Gigbyte offerings.
  • -9 Hide
    nevertell , October 28, 2009 9:11 AM
    Dunno, I think the i7 920 is still better.
  • 6 Hide
    coconutboy , October 28, 2009 10:44 AM
    i7 920 should be better, it costs an extra $100+ for an x58 mobo that is equivalent to its p55 counterpart. Yet, at stock speeds i7 920 loses to 860 in nearly every app and when both cpus are OC'd, it's still close enough that most people will ask themselves if it's worth the extra $$ for x58. i7 920's main advantages are:

    ~ dual-CPU workstations
    ~ high-end triple/quad GPU gaming setups that will tax PCIe throughput
    ~ easy (relative to p55) 4GHz+ overclocks
    ~ bandwidth intensive tasks that make use of the 3rd RAM channel.
    ~ nearly a year headstart to stabilize drivers and mature the x58 mobos

    What seems to be more and more in doubt is if x58 is still better at:
    ~ stock/low voltage overclocks w/ little tweaking required to hit ~3.5-3.8GHz
  • -4 Hide
    curnel_D , October 28, 2009 2:34 PM
    Psycho SykesSorry if it's a noobish question.. but does this mean that it acts (the CPU) like an extreme edition CPU using this BIOS update?Please answer and don't flame or give a thumps down...

    No. The over-speed protection limits you from going past a certain power threshold. EE CPU's have unlocked multipliers, making overclocking extremely simplified.
  • 5 Hide
    curnel_D , October 28, 2009 3:01 PM
    Psycho SykesThank you..It's just that the video demo on Intel's site said the i7 EE as "... and over-speed protection removed ..." So i thought it was it...Still the "making overclocking extremely simplified." thing doesn't worth the $700+ premium price (the QX9750 is priced higher than the i7 975 i believe, just because it's the LGA775's flagship!)..Medo

    Originally, you could only disable over-speed protection on the EE i7. Shortly after release, Intel changed their minds for whatever reason (Likely very bad publicity), and fixed that issue. Now it's entirely up to motherboard manf's to decide to include the feature to disable it.

    And you're totally right, there's not much of anything worth the $700 price premium. The EE processors are more for people that either have more cash than sense or who want the fastest available, but who don't want to inherit the risks from overclocking.
  • 0 Hide
    bustapr , October 28, 2009 3:04 PM
    Wow, the performance per watt of the turbo was a little too hogh, but the app boosts are incredible, gaining over %33 productivity. Thats a great o/c to an already great cpu. Good article Pat & Ach.
  • 0 Hide
    deadlockedworld , October 28, 2009 3:22 PM
    This is great. It would be nice to see these numbers side-by-side with some other processors (AMD?) for comparison purposes though.
  • 0 Hide
    tecmo34 , October 28, 2009 3:26 PM
    nevertellDunno, I think the i7 920 is still better.

    I agree with you... but of course I have a i7 920 :D 

    I like the thought of upgrading to the Intel Hex core next year over the current benefits of the i5 750 cost to performance.
  • 0 Hide
    billiardicus , October 28, 2009 3:36 PM
    Good article. I'd like to to see come comparisons with the i7 920/940 though.
  • 0 Hide
    Finglor , October 28, 2009 3:38 PM
    Is there anything else that needs to be changed for overclocking without voltage modifications?Is it possoble to say set the 133 base clock to 160 and be stable without doing anything else?
  • 4 Hide
    kufan64 , October 28, 2009 4:17 PM
    Interesting article. I'm a little suprised they didn't show any comparisons with the i7 920, but I guess they wanted to focus on LGA 1156.
  • 3 Hide
    Pei-chen , October 28, 2009 4:39 PM
    I wish you throw in a PII X4 at similar OCed speed just to show scaling. A 955 UC/OC to 2.66, 2.8, 4.0 & 4.2 will be very interesting to see as many people are saying PII @ 4.0GHz = i5 @ 4.0GHz which I think is not true.
  • 5 Hide
    Summer Leigh Castle , October 28, 2009 5:44 PM
    Pei-chenI wish you throw in a PII X4 at similar OCed speed just to show scaling. A 955 UC/OC to 2.66, 2.8, 4.0 & 4.2 will be very interesting to see as many people are saying PII @ 4.0GHz = i5 @ 4.0GHz which I think is not true.

    An i5 750 @ 2.66 (stock) is already faster than a PII 965 @ 3.4 (stock). What makes you think it's going to be any closer when you push the i5 to 4.0?
  • 1 Hide
    mapesdhs , October 28, 2009 6:46 PM

    Patrick/Achim, there's something I don't understand re your choice
    of comparison CPU. The article states early on that the 870 doesn't
    make any sense from a cost perspective, so why is it in the
    graphs? Surely you should have compared to the 860? And indeed,
    seeing how an 860 oc's is exactly what I would have thought most
    people would want to know, since that is the most comparable CPU
    to the 920. Paired into graphs with 750 results, it would be
    genuinely useful to see how a 750 compares to an 860 on P55, ie.
    whether the extra cost of the 860 is worthwhile (offhand, I had
    assumed it would be) and by that I mean via including both stock
    and best-oc 860 results.

    Thus, can you please check with an 860 aswell? For most enthusiasts,
    the 870 is not relevant. Likewise, how high can an 860 oc without
    a voltage increase on that board? Does its higher base clock help?

    Ian.

  • -1 Hide
    Anonymous , October 28, 2009 7:00 PM
    I'm going to get bashed for this but amd and intel chips do scale a bit different, but I do think this chip is sweet, and is worth the money. I would never be able to argue that my p920 could beat this chip. I was at a little overclocking comp a while ago and the chip that beat all the i7 and p2 was one of those big fat 775 chips clocked to high hell lol. so I don't know what to do anymore.
  • 0 Hide
    porksmuggler , October 28, 2009 7:30 PM
    if you guys are going to do an overclocking article, at least try to not confuse readers with voltage terminology. You mentioned increasing the PCH at 4.0GHz, then show the PCH in the 1.8-1.9v range??? The PCH is the southbridge, and doesn't really need to be adjusted beyond the nominal 1.05v. The voltage range you are showing is that for the CPU PLL (I know they call it PCH_1.8v at MSI). Also, 1.45v for 4.0GHz, yep definitely a MSI board, that's horrible.
  • -2 Hide
    surda , October 28, 2009 7:51 PM
    very interesting, though i would really like to see how far can i7 920 be overclocked and being stable.
  • 2 Hide
    coopchennick , October 28, 2009 7:51 PM
    Do we know if this particular board has a foxconn socket?
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