700mhz eMac CPU Overclock

Discussion in 'PowerPC Macs' started by bigbadmac, Feb 22, 2005.

  1. macrumors member


    Jan 12, 2004
    Washington State
    Hi all! I've been getting quite a few emails and even a few phone calls about my old 700mhz overclock site. I sold Studio-Northwest.com and therefore no longer have the domain name that I was using for my hakz page.

    However, I'm working on a new site for all you 700mhz eMac owners to visit. Until I get it up and running, I'll take Questions here and post the replies for all to see.

    I'm going to post a few basics right up front to get you started. Best of luck to you all and stay tuned for the new site on its way.
  2. thread starter macrumors member


    Jan 12, 2004
    Washington State

    I'm assuming you all know that your are the only one resposible should something go wrong. That said, let's get started.

    I set up my eMac so I can change the jumper settings at any time without taking the eMac appart. Although I only cover modding the eMac in this way, you can use the basic info to do a straight solder bridge overclock if you wish. I did the mod with a changeable jumper so I could experiment with the different settings.
  3. thread starter macrumors member


    Jan 12, 2004
    Washington State
    Items you'll need...

    Here's what you'll need to mod your eMac the same way I did...

    Basic Materials: jumper jack ( I salvaged one off a dead SCSI drive ), Ribbon Cable, Solder, Solder Paste ( easier to use than solder ), Flux, Solder Wick, Soldering Iron ( adjustable temp preffered )

    Attached Files:

  4. macrumors 603


    Jul 17, 2004
  5. thread starter macrumors member


    Jan 12, 2004
    Washington State
    Motherboard Prep

    Remove the motherboard from your eMac. ( I'll get a link up later for instruction for this )

    The area we want to remove the old jumpers is located on the bottom of the MB, same side as your RAM modules. I've highlighted the area in red.

    Attached Files:

  6. thread starter macrumors member


    Jan 12, 2004
    Washington State

  7. thread starter macrumors member


    Jan 12, 2004
    Washington State
    MB Prep Step 2

    Here's an image of the highlighted area. There are 5 jumper positions for the CPU clock control. They are R1506, R1509, R1512, R1515, and R1518. R1512 was not installed on my eMac

    Attached Files:

  8. thread starter macrumors member


    Jan 12, 2004
    Washington State
    Clock Settings

    Here's the shortcut version:

    Prior to removing any jumpers, take a look at the table below. Only remove the jumpers you have to to get the disired CPU overclock. To create a jumper, us enough solder to bridge the pads.

    Since the table was made for my jumper connector, here's a cross reference to the Resistor numbers.

    R1506 = A1 and A2
    R1509 = B1 and B2
    R1512 = C1 and C2
    R1515 = D1 and D2
    R1518 = E1 and E2

    Attached Files:

  9. thread starter macrumors member


    Jan 12, 2004
    Washington State
    Quick Overclock....

    So... to do a quick overclock, here's the combination of removing jumpers to give you the speeds that are tested. I'm only listing speed that can be atained without having to solder anything in place.

    850 MHz: Remove R1509. This is tested STABLE.

    900 MHz: Remove R1509, R1515, and R1518. This is tested STABLE.

    950 MHz: Remove R1509 and R1515. This is tested STABLE running a little HOT.

    1.0 GHz: Remove R1506 and R1518. This is UNTESTED. May cause system lockups and CPU overheating.

    That's it for now... if you want to know how I did the changeable jumpers, request it here and I'll post more info... Good Luck, and let me know how it goes.
  10. macrumors newbie

    Feb 18, 2005
    700mhz emac to ATX p/s ...Voltage pinouts???

    I have an eMac 700 Generation 1 logic board.

    I am interested in making this thing work.
    I have spent nearly 4 hours of reading all of the forums I can find and looked at all of the iMac conversions that have been done and the g2 eMac conversions but allas none of those help as this board is totally different.

    I have ram, HD, CD-RW, ATX case and 400w ATX p/s, and a 17" external monitor.

    1) Has anyone figured out the pins for the down converter connector (mine has 20 pins)
    2) Has anyone figured out the blind mate connector for the video and which one to use? (mine has 2 of them)
  11. thread starter macrumors member


    Jan 12, 2004
    Washington State

    Check the 800 MHz thread. I passed my eMac to my younger brother and am now on an iBook... I would venture to say that the pinouts would be the same or close to the 800. I beleive Leo has that info.

    800 MHz thread
  12. macrumors newbie

    Feb 18, 2005
    I have looked throught that ...

    I have looked through that post till I am blue in the face LOL and still nothing about the GEN 1 emac....I just bought a 700mhz emac but now I am wondering if I can power the LOGIC BOARD using the voltages on the DOWN CONVERTER board connector or if I actually have to power the LOGIC BOARD from a BLIND MATE connector? What concerns me is to use the BLIND MATE, I have to get a DOWN CONVERTER board.
  13. thread starter macrumors member


    Jan 12, 2004
    Washington State
    Down Converter

    You could probably make this work without the down converter but you're back to square one needing the pinnout. I should have kept the ole' 700 for further work on these mods. My brother really needed a Mac so I sent it off. I'll do a little digging around and see if I can come up with some info... I seem to recal some sites in Japan that had some info. More later...
  14. macrumors newbie

    Feb 18, 2005
    700mhz Gen1 Bind-mate connectors and Down Converter Pinouts!!

    Ok I bought a 700mhz mac off of eBay to just get these voltages!!!

    ok here are the updated Blind-Mate pin outs with the proper polarizations...

    Blind-mate nearest CPU

    PIN, OFF, ON
    1, 12.14v, 18.43v
    3, 7.3v, 11v
    5, 7.3v, 11v
    7, 0, 0.4v
    9, 13.89v, 0.71v
    11, 5v, 5v
    13, 0.115v, 12v
    15, 0.115v, 12v
    17, 0.115v, 12v
    19, 11.13v, 17.41v
    pins 2,4,6,8,10,12,14,16,18, and 20 were all GND

    Blind-mate nearest External Connections
    1 Mic (+)
    2 Mic Signal
    3 Mic GND
    4 Mic GND
    5 Light (+)
    6 Light (-)
    11 Fan Sense (RPM)
    13 Right Speaker (+)
    15 Right Speaker (-)
    17 Left Speaker (-)
    18 Fan GND
    19 Left Speaker (+)
    20 Fan 12v
    Pins 7,8,9,10,12,14, and 16 had no connections
    * notice that pins 15 and 17 were the (-) for the speakers this would support comon ground.
  15. macrumors newbie

    Apr 13, 2005
    800Mhz GeForce2 MX eMac

    Hi, is this the right thread for looking at overclocking my 800Mhz GeForce2 MX eMac that i purchased form Apple in Oct 2002.

    The reason i ask is that i gather from reading the posts that 700Mhz tends to imply Gen 1, 800 Mhz = Gen 2, (maybe 1Ghz = Gen3?).

    That said, has anybody had success overclocking a 800Mhz Gen 1. What reliable max speed did they see? Is the 7455 shipped in the 800Mhz Gen 1 machine more likely to reach the 1Ghz 'max' that is implied in posting #8...?

  16. macrumors newbie

    May 28, 2005
    Is R1509 the jumper by the carat ( > ) , in the MB prep photo? :confused:
  17. macrumors newbie

    Jan 13, 2005
    Granada - Spain
    I have a Gen1 700 Mhz GeForce2 MX eMac equipped with an 7455 G4 processor, and I've been able to overclock it up to 1.2 Ghz without any problem. I have not even needed to raise the CPU voltage. You just have to find the Motorola MPC7455 data sheet (pdf) and adjust the pinout to whichever speed your computer is stable.

    I have to say that my eMac is less stable at 1.2 Ghz than before the speed bump, but I have lowered it's speed up to 1.1 Ghz and now it runs flawlessly.

    If you have any question, just say it...
  18. macrumors newbie

    Jun 13, 2005

    So I loaded Tiger on my emac 700 and found it too slow. So I came to this thread looking for answers. I've recently upgraded the HDD to a 160 GB Western Digital and the optical drive to a Pioneer DVR-109 superdrive. So I'm comfortable working inside the emac.

    I overclocked my emac to 900 Mhz, which is marked as stable above.


    I rebooted, and to test for a performance gain, I attempted to play a DVD in a window and surf on Safari at the same time (the About This Mac screen showed 900Mhz G4). Then it locked up about a minute later and I had to use the power button to turn it off. I waited about 10 minutes, then turned her back on. I got booted up, but almost as soon as I had, I got a kernal panic. Now I'm scared to turn it back on!

    I can't imagine what I've done differently than anybody else. I just flicked those little jumpers off the mobo with an exacto knife; and no, I didn't hit anything else on the board whilst I was doing it. I heard tell of 1.1 Ghz running stable on someone else's emac, so why the poor show on mine?

    Help! I seriously doubt that I can solder anything that tiny.
  19. thread starter macrumors member


    Jan 12, 2004
    Washington State
    Proper Tools and Technique

    Just a reminder to all who want to overclock their eMacs. If you are not sure how to properly desolder components, your eMac is not where you want to practice. Buy a cheap calculator or something like that to practice on. You want to be able to remove components without damage to the board and idealy, solder the components back on and have the unit work.

    If you do not have the proper tools and technique, the chance of doing damage goes up significantly. I cannot stress this enough as I have seen several bad experiences on this hack. If you're not sure or comfortable with your tools or skills, JUST DON'T DO IT!
  20. macrumors newbie

    Jul 4, 2005
  21. macrumors newbie

    Jul 30, 2005
    Thanks to guylan for his pinouts.

    I'm planning on resurrecting a 700MHz eMac with and ATX Power Supply and an Apple VGA Display Adapter for the video signal (as I'm not sure where the VGA pins are on the logic board). [Found 'em. See my next posting below.]

    I'd like to keep the Down Converter per Leo Bodnar's Headless eMac <http://www.lbodnar.dsl.pipex.com/eServer/>, but I'm concerned about his providing only 12V in placed where 20V are used.

    "...I suggest to keep the down-converter board. You can, of course, get 12V, 5V and 3.3V from a standard ATX power supply but then you need to generate 2.5V. Linear regulator should be enough as this is not a high current circuit. After all the trouble with breadboards you will wish you'd kept the down-converter. If you are trying to fit eMac into a slim case you can always turn DCB on its side and use ribbon cable to connect it to LB."

    "We take an easy route here and use 12V to replace original 20V and 19V power. The result is that DCB cannot produce 12V out of 12V so the DCB output reaches only about 11V which may be too low for HDD or optical drive. But as I said above, get drives powered up by PSU directly to solve that."

    Has anybody successfully used an ATX Power Supply working using the Down Converter on an eMac 700MHz logic board?
  22. macrumors 68020

    Mar 30, 2004
    So practically speaking... we have an eMac/700 in our house, for nothing too demanding, I definitely notice the slowness though in everyday tasks. Does a jump to 900 make it that much faster? Opinions?

    So true... I picture the film "Psycho", an exacto-knife, jumpers flying... *cue dentist drill horror sound effects*

    When a chip comes off the fab, they have different qualities, because a chemical process is never perfect or 100% exact. The chip makers use speed standards, essentially hertz, to measure this. When you buy your computer it's rated at a given speed, say 700Mhz. It may be able to run faster, but the manufacturer (Apple, Dell) will "clock-down" to differentiate models and create price segments. Some chips may never go faster than their rated speed... others can go far beyond. Overclocking, then, is finding the limit.

    So basically... you may need to solder afterall. Overclocking is also about patience and tweaking until it's just right. Sorry mate. I know you can do it!
  23. macrumors newbie

    Jun 29, 2005

    After reading all this and and rereading this i finally decided to give it a try. At first I tried a 133 fsb change. No go. Replaced it back to 100 fsb and everything is fine. THen I reread this forum and try to go from a 800mhz Gen1 to a 950mhz gen1. No go. Then I realize that I have another resistor missing...maybe I knocked it off when I remove one of the others. So i make a bridge for that jumper. I compare it to the pictures posted here and everything looks right. It chimes, the light on the front comes on but then......nada. Anyone have any ideas? I am tired of looking through a magnifying glass. I have done lots of other hacks, ps, xbox, and so forth. I have a little time with the soldering iron under my belt but right now I am screwed..
  24. macrumors newbie

    Jul 30, 2005
    eMac 700 video on logic board

    I found the video connector near the heat-sinked video chip on the logic board (see upper right of logic board). It's clear which are the RGB and HSYNC and VSYNC pins. Once I figure out the ???s, I'll try putting a VGA connector on the other end of the original video cable to the logic board.

    eMac 700 Video Connector:
             1    2  
    B video  3    4  B Return
    G video  5    6  G Return
    R video  7    8  R Return
        ???  9   10  ???
     V sync  11  12  ???
     H sync  13  14  ???
        ???  15  16  ???
        ???  17  18  

    Attached Files:

  25. macrumors newbie

    Oct 11, 2004

    hi people,

    I have a big problem i done this mod and i put the computer back together. plugged her into the wall pushed the power button it starts up light comes on at the front etc it makes the sound but nothing comes up onto the screen? Whats going on?

    Please can someone help?

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