To facilitate our Core i7/X58 motherboard testing, we have been snapping up retail CPU’s from a variety of outlets in the US and Europe. Since most of the users adopting this platform are opting for a Core i7 920 as their mainstay processor, we have been on a buying spree for this particular model while also dropping some hard earned cash for a couple of the 940 and 965XE retail processors.

I purchased my first 920 over three weeks ago from SCAN UK. This particular CPU is a 3838A batch processor, which I proceeded to test in the Foxconn Bloodrage and EVGA X58 SLI motherboards. It’s the same old story really when it comes to clocking, I scoured the forums, spoke with Gary and Kris (who had a head start on me with this platform) and asked them the lowdown of what to expect in terms of voltage related scaling hoping that I had something at least as good if not better than their retail processors.

Like many others out there, I was hoping for a processor that could clock to 4GHz and beyond at fairly low processor core and VTT voltages. This together with an IMC that could handle triple channel speeds well above 1600MHz, actually, make that 2000MHz. The kind of speeds I’d seen posted on various overclocking forums using the 920 processors had voltages just tolerable enough for 24/7 use. I must also add at this point that some of the testing we do on these boards falls well outside the 24/7 bracket. An ever increasing number of boards are released solely with benchmarking in mind, a growing segment of the industry that seems to be on the fringe of demanding complete segregation from mainstream products due to its specialized needs.

A large part of testing these boards involves running both entry-level and high-end components well out of specification ranges, just to see what a particular board can do if pushed or if it will go up in a ball of smoke, something Gary seems to master at times. This may seem trivial to most of our readership, but it’s an ever growing part of the enthusiast sector and somebody around here has to test it, so in comes my need for decent components, especially processors in this case.

While this processor matched the ‘international average’ for core voltage scaling, I discovered that I had to apply ridiculous levels of VTT/Uncore voltage to get it to boot at anything over 185BCLK. A 3.8GHz clock speed fell with relative ease, but pushing up to 4GHz, well that’s where things became real tricky. This processor seems to stop in its tracks with VTT voltage levels over 1.36V (just outside the warranty maximum by the way) or so, causing both of the motherboards to halt during POST with a C1 error.

Manipulating voltages within the OS using motherboard specific software tools can circumvent this condition to an extent, but the voltage has to be ramped up in small steps. Either way, 4GHz stable on this particular processor is way more hassle than it could ever be worth in a 24/7 system so I am stuck at 3.8GHz. Ok, this seems a bit demanding of me, a free 1.2GHz overclock from stock and I’m nowhere near happy! In fact, at this point I was pretty much convinced that both of the motherboards I was testing were duff, not the CPU, especially when I looked over at some of Gary’s early results on the same boards, as well as results of forum members.

I conferred back with Gary on his results, he’s got three retail 920s in his repertoire (with a fourth on its way) and his results are erratic in this department too. One of his processors needs high levels of Vcore to make 4GHz possible, well in excess of 1.50V, and refuses to POST with Bclk ratios set higher than 200, regardless of VTT/Core voltages. The other two (3837A)are better than mine for IMC VTT scaling and can also handle 6GB triple channel memory at 2000+MHz with a little persuasion. Something I found impossible on my 3838A processor with 3GB of memory let alone 6GB. Also, both of his processors allow for 3.8GHz operation at stock or below stock core voltages with VTT near 1.15V. Both processors allow clock speeds to reach about 4.3GHz on 1.45V of VCore, but VTT required is near 1.425V on air cooling with a 2:8 memory ratio, change the memory ratio to 2:10 for DDR3-2000 and VTT requirements hit 1.50V, which also happens to be the maximum amount his processors will allow before throwing up a C1 code on POST.

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  • cooklaw - Saturday, February 21, 2009 - link

    dell.com/xps Reply
  • 529th - Sunday, January 25, 2009 - link

    Thanks for the article/research. I've found this interesting. I also have a 3838A687 920 that I got on sale (229$) that I'm almost willing to lend for some overclocking results...???... but from what I make of this is that the motherboard tolerances are a bit more key to its overclockability; am i correct? Looking forward to your follow up article between the motherboards.

    P.S. i7 build is not up-n-running yet, ETA 6 months, lol
    Reply
  • Rajinder Gill - Sunday, January 25, 2009 - link

    Hi,

    Just been testing a couple of ES 965's, 3830A and yet another 3838A. The 3838 is on a par with my weaker 920 using air/water cooling. The 3830A 965, is still not as good as the 3835A 920 retail. Out of 4 CPU's, I only have on that can run tight CAS at higher BCLK. WIth the 965's it's a little moot as you can use the higher multipliers, although I still find that the 3830A (the better 965), needs waaay more Uncore voltage and even then it's nowhere near Prime stable like the 3835A 920.

    Sub-zero cooling, the 965 3838 cold bugs very early, making it a poor clocker both sides of the spectrum. The 3830A 965 is a little better but I have not managed to get it stable for 3D past 4.6GHz.

    regards
    Raja
    Reply
  • eva2000 - Monday, February 09, 2009 - link

    Definitely can confirm that cpus will differ in terms of CPU VTT, tested 2x i7 920 3836A756 and CPU VTT handling differences are huge http://i4memory.com/105269-post4.html">http://i4memory.com/105269-post4.html !

    i7 920 3836A756 #1

    * max memtest86+ bootable bclk = 224 requiring 1.58-1.60v CPU VTT
    * max super pi 32m bclk = 222bclk (without IOH/ICH voltage tweaks) & 228bclk (with IOH/ICH voltage tweaks) requiring 1.60-1.61v CPU VTT
    * max CPUZ Validation = 230bclk requiring 1.60-1.63v CPU VTT


    i7 920 3836A756 #2

    * max memtest86+ bootable bclk = 229bclk requiring 1.40-1.48v CPU VTT
    * max super pi 32m bclk = 225bclk (without IOH/ICH voltage tweaks) & ???bclk (with IOH/ICH voltage tweaks TBD) requiring 1.48-1.50v CPU VTT
    * max CPUZ Validation = 231bclk requiring 1.50v CPU VTT

    2nd cpu also likes vcore closer to cpu vtt for stability whereas 1st cpu didn't have such a strict requirement.
    Reply
  • DrMrLordX - Sunday, January 25, 2009 - link

    That's very interesting. Did anyone get the coldbug with Penryn-class quads? This certainly puts Phenom II in a different light since it has been demoed at 6 ghz under LN2 and 6.3 ghz under LHe2 (suicide runs only, of course). Reply
  • CSGLEON - Saturday, January 24, 2009 - link

    i know this might be a little off topic but....
    would i be able to tell much of a differnce between a Intel Core 2 Quad Q9550 Yorkfield 2.83GHz and a Intel Core i7 920 Nehalem 2.66GHz? i play games and need to upgrad my cpu. but would have to upgrade everything for a i7 and spend a lot more money.



    Reply
  • Iketh - Saturday, January 24, 2009 - link

    for the most part no Reply
  • aigomorla - Friday, January 23, 2009 - link

    i absolutley love i7 bashing.

    Its funny how only a handful of people actually got it for something useful.

    I used to hold the largest 4ghz yorkfield collection on this forum.

    I also hold one of the most expensive h2o systems on this forum/site.

    If you got an i7 because it was a FAD thing, and u had to jump the wagon, then shame on you.

    If you got the i7 knowing what your getting, because u actually use the 8 threads it offers, then its a win.

    Theres 2 different sides in people when it comes to computers.
    1. think there just an upgraded form of a calculator.
    2. think of it as art, and to tune and unlock that art, is a whole another world.
    Reply
  • Cuhulainn - Sunday, January 25, 2009 - link

    I absolutley(sic) love bragging.

    So impressed.
    Reply
  • marc1000 - Friday, January 23, 2009 - link

    somebody already asked of them? AMD has greater expertise with the IMC, even if the cores are not as powerfull as the cores of the i7. how weel do theyr new cpu overclocks? Reply

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