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Picking CPU's by BATCH (Cherry Picking)

Discussion in 'Overclocking & Cooling' started by AthlonX2, Dec 27, 2011.

  1. AthlonX2

    AthlonX2 HyperVtX™

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    Picking CPUs by batch.

    Intel

    An Intel "batch" code looks something like this.
    3849A015

    3 - Plant it was made at, list of plants.

    0 = San Jose, Costa Rica
    1 = Cavite, Philippines
    3 = .............., Costa Rica
    6 = Chandler, Arizona
    7 = .........., Philippines
    8 = Leixlip, Ireland
    9 = Penang, Malaysia
    L = ............, Malaysia
    Q = ..........., Malaysia
    R = Manila, Philippines
    Y = Leixlip, Ireland

    8 - Year (2008)
    49 - Week of the year (49th week)
    A - Stepping (A less voltage more heat, B more voltage less heat, C too rare to know advantages)
    015 - Location on the wafer. Last two digits are important, you want them to be less then 15.


    Whats important. Firstly, the date (year and week). Only way to know which are best is by looking for results by others with the same date.
    Next look at the stepping. Decide by your cooling. I recomend A batches for good water setups for daily, and since they are generally lower VID then B batches, should be better with extreme cooling. B batches are going to be better for air, or entry water setups. They will also generally draw less power.




    AMD is a little more confusing, since there are so many numbers. One would look like this.

    CCBBE CB 1023FPMW
    Y460944J00399

    CCBBE is is the stepping code.
    1023 is the date (2010, 23rd week)
    F is the 6th day of the week, rest of the days are,

    G = 7th day:
    A/R = first day
    B/S = second day
    C/T = third day
    D/U = fourth day
    E/V = fifth day
    F/W = sixth day
    G/X = seventh day

    P is the location, MW means multi wafer.

    The last three digits of the bottom line is the location on the wafer. The lower the better.


    Ok, so when picking an AMD CPU by batch code, you go to pick the best week first, its the most important. For Deneb, 1010 were good and for Thuban 1015 was good. If you find more then one with the same week, then look at the bottom line, last three digits. Go with the smaller number.





    Common Mistakes


    Low VID vs high VID

    A low VID sample is going to be a high leakage chip (good for benching with extreme cooling, high VID is better for daily). VID is determined by TDP. If a CPU has a TDP of 125W, when they are setting the VID, they are setting it so it does not go over the TDP. If the range for a certain CPU is 1.2-1.5, and a CPU is going past the 125W TDP, they will give it a low VID. So a 1.25v CPU would be a low VID CPU, but a high leakage CPU. Now you take that 1.25VID CPU, and set it to 1.4V, it will now be drawing more power then a high VID CPU that started at 1.4V.



    So in reality, for a daily system or system cooled by air or water, you DO NOT want a low VID CPU. They are better then high VID CPUs for LN2 or other xtreme cooling though.

    AMD

    CPU/NB Speed
    For Deneb and Thuban CPUs, the CPU/NB speed can make much larger impacts then in the past. It can greatly bottleneck your memory bandwith when too low, and using fast memory. The CPU/NB speed should be at least double or close to double the speed of the memory to not bottleneck it. If your CPU/NB speed is only 2000Mhz, there is no point in running the memory over 1333Mhz. The difference will be minimal at best. CPU/NB clocking used to have large negative effects on CPU clocking, now its not nearly as much. Yes you are likely going to need to increase the CPU/NB voltage to get higher speeds, but the negative effect will mostly be to the motherboard. With current motherboards, most should be able to handle high CPU/NB speeds without effecting the clocking of the CPU.

    VID

    A voltage regulator module or VRM, sometimes called PPM (processor power module), is a buck converter that provides a microprocessor the appropriate supply voltage, converting +5 V or +12 V to a much lower voltage required by the CPU. Some are soldered to the motherboard while others are installed in an open slot. It allows processors with different supply voltage to be mounted on the same motherboard. Most modern CPUs require less than 1.5 volts. CPU designers tend to design to smaller CPU core voltages; lower voltages help reduce CPU power dissipation, often referred to as TDP or Thermal Design Power

    Some voltage regulators provide a fixed supply voltage to the processor, but most of them sense the required supply voltage from the processor, essentially acting as a continuously-variable adjustable regulator. In particular, VRMs that are soldered to the motherboard are supposed to do the sensing, according to the Intel specification.


    The correct supply voltage is communicated by the microprocessor to the VRM at startup via a number of bits called VID (voltage identification). In particular, the VRM initially provides a standard supply voltage to the VID logic, which is the part of the processor whose only aim is to then send the VID to the VRM. When the VRM has received the VID identifying the required supply voltage, it starts acting as a voltage regulator, providing the required constant voltage supply to the processor.

    Instead of having a power supply unit generate some fixed voltage, the CPU uses a small set of digital signals, the VID lines, to instruct an on-board power converter of the desired voltage level. The switch-mode buck converter then adjusts its output accordingly. The flexibility so obtained makes it possible to use the same power supply unit for CPUs with somewhat different nominal supply voltages and to reduce power consumption during idle periods by lowering the supply voltage.

    For example, a unit with 5-bit VID would output one of at most 32 (25) distinct output voltages. These voltages are usually (but not always) evenly spaced within a given range. Some of the code words may be reserved for special functions such as shutting down the unit, hence a 5-bit VID unit may have fewer than 32 output voltage levels. How the numerical codes map to supply voltages is typically specified in tables provided by component manufacturers. As of 2008 VID comes in 5-, 6- and 8-bit varieties and is mostly applied to power modules outputting between 0.5V and 3.5V.






    Source
     
    Last edited: Dec 27, 2011
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  2. JustaTinkerer New Member

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    Very nice, glad I know that now. I always new the Intel but could never find the AMD code, anything I did find about it I didn't truly understand.
     
  3. Sasqui

    Sasqui

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    I understood stepping to be be a "revision" to the chip in some form. Usually, the higher the character, the later the rev, at least on intel chips.

    Can you document the VID acronym?

    Thanks!
     
  4. AthlonX2

    AthlonX2 HyperVtX™

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    I added some info on VID, what i could find on it anyways
     
  5. MGF Derp

    MGF Derp

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    Hasn't it been argued that binning is more of a complete gamble nowadays and less of good batches and bad batches like it used to be? At least thats what I have heard about Sandy Bridge.
     
  6. AthlonX2

    AthlonX2 HyperVtX™

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    Im not sure how well it works anymore,I posted this because it took me half a day of google searching to pull any information on the old binning process.
     
  7. Sasqui

    Sasqui

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    I have to ask, why? Number on the wafer is probably dependant on how they assign the chip numbers per wafer, starting with the first good (complete) one and moving in row or column to the last good one.

    And, what does location on the wafer have to do with the quality? Are ones near the middle better than ones on the sides?
     
  8. AthlonX2

    AthlonX2 HyperVtX™

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    It was rumored long ago that the best chips were in the center of the wafer moving out in a circular pattern
     
  9. EarthDog

    EarthDog

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    This is generally true of SB and so far SB-E. No clue about AMD.
     
  10. scaminatrix

    scaminatrix

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    The only thing that can prove this is the numbers. Come on OC'ers, post your OC's and chip details!
     
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  11. EarthDog

    EarthDog

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    There are barch threads everywhere already.
     
  12. scaminatrix

    scaminatrix

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    I bought myself a 1055t for Christmas; numbers are:

    CCBBE CB 1134FPM

    9U.....I10142

    Week 34 of 2011 = August 22 to August 28 so nice and new, 142 doesn't seem low though :laugh:

    Haven't installed it yet
     
  13. AthlonX2

    AthlonX2 HyperVtX™

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    my 1090T is #74 and hits around 4.6Ghz
     
  14. scaminatrix

    scaminatrix

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    Nice! what week/year is it?
     
  15. AthlonX2

    AthlonX2 HyperVtX™

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    Made on Friday 4th of June 2010
     
  16. cdawall where the hell are my stars

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    Good little write up. Will look up some of my steppings for reference.
     
  17. LAN_deRf_HA

    LAN_deRf_HA

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    How do you find the vid on a sandy bridge? Seems the boards ignore vid and just go by clock speed when on auto, either that or every 2x00k build I've done has had the exact same vid.
     
  18. HUSKIE

    HUSKIE

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    O.T

    0 = San Jose, Costa Rica
    1 = Cavite, Philippines- THIS IS MY HOMETOWN
    3 = .............., Costa Rica
    6 = Chandler, Arizona
    7 = .........., Philippines
    8 = Leixlip, Ireland
    9 = Penang, Malaysia
    L = ............, Malaysia
    Q = ..........., Malaysia
    R = Manila, Philippines
    Y = Leixlip, Ireland
     
  19. Arctucas

    Arctucas

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    CPU - i7 950 Batch #3008A996

    Clocked at 4273 MHz, (21x204 in BIOS) 24/7, 20 pass LinX stable, @1.35V.

    I can clock up to 4.41 GHz and use Windows @1.4V, but it fails LinX.

    So, I am wondering about the last three numbers, unless the 'better' chips from that wafer are absolutely exceptional?
     
  20. OOZMAN

    OOZMAN New Member

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    Why do you have a Duron system in your system specs then? :confused:
     
  21. cdawall where the hell are my stars

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    Probably the same reason I have an Xeon in mine and yet have done all of these
     
  22. OOZMAN

    OOZMAN New Member

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    Still don't understand. :wtf:
     
  23. AthlonX2

    AthlonX2 HyperVtX™

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    hmm...I have a number of pc's in the house,and i just so happened to put the duron in my specs because it was my first pc i owned. doesnt mean i dont have other, better PC's
     

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