PLL Pinmod Overclocking Methods and Examples

Discussion in 'Hardware Components and Aftermarket Upgrades' started by moral hazard, Jun 24, 2009.

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  1. jotm

    jotm Notebook Evangelist

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    You should be able to overclock the 6910p with a pll mod. The SLG8SP512T goes up to 1600 MHz (400 MHz x4), so that's not a problem.

    The T9300 has an 800 MHz FSB = 200 MHz x4, so the mod seems rather easy - connect FS_B to ground via a ~10k resistor. That should give you 3.3 GHz or 3.5 GHz with dual IDA. Soldering is the hardest part, though...

    The problem will be with the RAM and CPU voltage, but you can flash the RAM using SPDTool and as for the CPU voltage, I'd recommend using a modded BIOS that disables EIST on boot so you can boot with the CPU at the lowest frequency, then use Throttlestop to set it to 3.3 GHz and set as low a voltage as possible.

    That's what I did with my 8530p and it works great, I believe the 6910p BIOS should be just as easy to mod. I'm finishing the modding right now, I'll report back after assembling my laptop.

    I don't know about TME unlock, it was really hard on my laptop, but the PLL FSB hardmod doesn't depend on it (in fact you can probably do them both)...
     
  2. Hurricane3000

    Hurricane3000 Newbie

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    Thanks for reply.
    I'd prefer do not mod Bios (actually I have the latest HP 1.7), UNLESS I am sure that the new one only solve problems and not creates others, and mainly that remains to me possibility to come back (downgrade) if something is wrong.
    Then I think that only I will mod the PLL pin FS_B.
    But what about the compatibility of the chipset GM965 with a FSB of 1066 Mhz?

    Another thing that I not understood is:
    I have FS_B / TEST_MODE on Pin 57, and GROUND_REF on pin 58 (See pictures).
    Probably this is an ideal condition, if I can short directly Pin 57 and 58, but I think that so is not correct.
    I will must desoldering pin 57 before to connect it to Ground?

    PLL Pins.jpg FS Table.jpg
     
  3. jotm

    jotm Notebook Evangelist

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    Yes, you'll need to cut off pin57 from the rest of the motherboard, so that makes it a bit more difficult (and hard to reverse).

    You must not short the pins directly. With the T9300, that would probably damage something.

    Ideally, you'd want to trace pin 57 further away from the chip (hopefully there's a long clear strip somewhere), cut its connection to the motherboard (with a box cutter, for example), then connect it to any ground point (even a screw nearby will do fine) via a ~10k resistor - this is pretty important. So the cable would go Pin57->resistor->Ground.

    You could just cut the pin57 connection and leave it at that, it should work but it's possible that it would occasionally lock up (especially when waking up from sleep). You can test this with the board outside the laptop and an external monitor, if it works fine, then there's no need for the resistor.

    PM965 will work at 1066 MHz, even 1333 probably, but you'll need to voltmod the CPU (OR use an edited BIOS), because the CPU would boot at 3.3GHz, and the default voltage won't be enough, so it would lock up or BSOD shortly after BIOS POST.

    RAM may need to be flashed because it would work at higher frequencies - in my case 800 MHZ RAM runs at 1000 MHz, so I flashed it down to 667 MHz and now it runs at 830 MHZ. In your case, you'll go from 667 MHz to 533 MHz, and also lower the timings to speed it up. But a lot of 1-2GB 667MHz modules will run fine without any mods.

    By the way, DON'T flash the latest HP BIOS (F19), as I think it's irreversible and you can't mod it - leave it at F17!
     
  4. Hurricane3000

    Hurricane3000 Newbie

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    Thanks a lot for your detailed explaination.

    If I cut Pin 57 and I connect it to ground via a 10K resistor, the TEST_MODE function of the pin may be it will be lost (as I think). Or not?
    About the BIOS update It's too late!!!!!!!!!!!
    When I read your reply I remembered that already updated my BIOS to Ver. 68MCU F.19 3 months ago!!!
    When I written my post I was convinced that the latest Ver. of HP BIOS was Ver F17, but in reality I have Ver. F19.
    It's a pity!
    I hope that this is not really irreversible, and hope that someone have tried to mod this Bios version.
    If I know correctly the "bad" BIOS version of your Lap is F.20. released in Dec 2011.
    Mine is been released in June 2010. May be that in that date HP not introduced yet the trap in the BIOS?
     
  5. jotm

    jotm Notebook Evangelist

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    It could be that the BIOS is not encrypted, which would be a good thing.

    TEST_MODE is useless for the user (it's activated when it detects a certain voltage, most likely 3.3V, and I'm not sure what it's used for, but it's not used in normal operation). For FSB settings, you either connect to ground (for a "0" on the table) or sub-1.5V (for a "1").

    If you're gonna try the mod, you'll need a multimeter and a small soldering iron or a DIY soldering tip.

    I could look for a good cut/soldering point if you can upload a few photos of the board around the PLL chip. Safest way would be to cut the trace somewhere where it would be easy to solder (and reconnect it if it doesn't work - with solder or just a pencil).

    But I gotta say that if you overheat the trace it can rip off the board and you can risk ruining it - if you're not experienced this mod is quite difficult (I found it rather easy but I've got some experience with this stuff and a good small soldering iron)...
     
  6. Hurricane3000

    Hurricane3000 Newbie

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    Hi,

    This mod can be made with a resonable safety and % of success only by peoples with a good experience in soldering.
    Fortunately I have.

    I read more carefully the datasheet of SLG8SP512P PLL, and I understood something important that probably may change/offer other point of view about the FSB pin mod.

    As you can see in the register table, the last 3 bits related to the FSB are "Read Only" bits.
    This means (as specified in the description column) that the PLL during the Power_Up read and sample the current state (Low/High) of the 3
    FSB_A/B/C pins, and store the 3 values in Bits 6,7,8 of his internal Register_0.

    After, FSB_A/B/C pins will can also ideally disconnected without problems and the set CPU clock will continue to be generated.
    In other words differentely from other PLL, in this chip the register_0 cannot be write by an external software ( i.e SetFSB) and probably for
    this reason SetFSB do not include the SLG8SP512P PLL in the list.

    Probably, this open other and new mod possibilities, for example to add a very simple electronic circuit (with very few components) able to
    generate a single brief Low-level pulse (i.e. 1 Sec.) to connect directly to Pin 57 (in my case), without any need to cut pcb traces or mod original circuit.

    For now this is only an idea and I will to study better this possibility, and also hope that someone more expert than me can give an help to evaluate and/or develop it.

    Register 0.jpg
     
  7. jotm

    jotm Notebook Evangelist

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    That's out of my area of expertise, but I think it would not be possible to set FS_B to "0" without cutting the pin's connection on the motherboard in this case since the CPU is setting it to "1".

    As I understand, these pins are set to "0" by default and set to "1" if voltage is sampled, which is why in my case (with the SLG8SP553V) I could do the mod by simply connecting a 3.3V line to pin7 via a resistor.

    So, since the CPU is trying to set it to "1" and your circuit would be trying to set it to "0" at the same time - it would just be set to "1", error out or worst case, be damaged - how can the chip choose what to write to the register?
     
  8. Hurricane3000

    Hurricane3000 Newbie

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    You are right, probably there is no way to avoid to cut pin and/or some track on PCB.
    I will must to inspect accurately the PCB around the PLL, with the hope to see some shorted bridge on the track that can avoid to cut it.
    I also will take some detailed photo of the PLL area and I will post it.
     
  9. 1el1

    1el1 Notebook Enthusiast

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    Thanks for the detailed reply. Just one quick question. Did you need to cut the FS_C pin before connecting it to the 3.3V?
    Thanks
     
  10. jotm

    jotm Notebook Evangelist

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    You don't need to cut it IF the processor is a 1066 FSB unit... It's possible even to wire the resistor through a switch or jumper so you can disable it without disassembling the laptop if need be...
     
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