eMac 800Mhz -> 1.33GHz conversion

If anyone's interested - eMac 1.25Ghz in a 2U rack



More pictures at the link at the bottom.

I spent a fair amount of time reading this thread before undertaking this project. Thanks for all the great information!

Basically I had an eMac with fried analog circuitry. I stripped it down to the board, added some standoffs, recycled a bunch of the parts/connectors.

By pure dumb luck, positioning the board so that the connecters were all pointed out the back of the rack case oriented the heat-sink fin assembly directly in front of the rear fan. The aluminum "L" bracket you see in the picture was actually cut out of a piece of the eMac's frame and provides a place for the heat-sink fin assembly to mount, keeping it rigid.

The blind-mate connecter was cut off then soldered to a $2 Radio Shack perfboard to provide a distribution point and plug-in for the +12VDC, +5VDC, and grounds. The perfboard was then mounted with a screw to one of the studs on the case that just "happened" to be in about the right place. With only a couple of inches of wire on the connecter, I had to kind of feel/plug it in when I mounted the board.

The rack case came with the standard LED and momentary rocker switch for power up. I just extended the cables off the old eMac to these. I also snagged the stereo speakers and just mounted them with one screw to an available stud. They work great.

I did run into the resolution problem using the on-board video, but was able to find a setting that would allow it to work. Bottom line is, it might have been easier to just purchase the $20 Mini-DV connector and move on than to go through the hellish soldering of a VGA female connector.

[Update 5/31/08 - I did purchase the Apple mini-VGA adapter and it is well worth it for the time you will spend dinking around with the onboard analog connector!]

I also wound up installing Leopard Server onto the drive via FireWire on another computer, setting the resolution there and enabling ARD. Worked like a champ. The problem with installing a system is that the installers always drop the resolution down, and in the case of the eMac, it drops it to a resolution that only the internal monitor supported, not one that a standard LCD supports.

Future enhancements:

Fix the back panel so that the power actually has a standard plug.

Find a way to hook up one of the front panel LED's to a hard drive activity LED.

Find the correct connectors and create a ribbon cable "extender" for the down-converter board. As it stands, I had to cut a sizable hole in the bottom of the case for the board to stick through about an inch. When I make a cable I will be able to lay it flat inside the case.

It's not too pretty, but it's been running Leopard Server now for about 24 hours with not one hitch and seems to be solid. Heat-sink fins run slightly warm to the touch, never hot.

Feel free to comment if you like. Pictures can be seen here:

http://www.packrat.net/eMacConversion

Old hat now...

I have done this mod so many times, it isn't even funny any more. Just last week, I got a load of 12 1Ghz emac's in, and have over clocked all but 4 of them. (Three have had trouble installing the OS, so i decided on the last 4 to install the OS first and then do the overclock, I just haven't gotten around to doing the overclock yet, but it is coming.)

Most of the machines hit the 1.47Ghz mark very easily, and all it required was removing 2 jumpers from the 1Ghz configuration. I am really quite impressed. The machines went from getting 12 pts in Xbench 1.3 running 10.2.9 to getting nearly 40 pts (after the OC) under 10.4.11. Can't beat that, can you.

These machines score better on most of the tests than my OC'ed 933 Mhz Dual G4 MDD.

Anyone who has reserves about blowing up their computer for doing this, forget them. The eMac is the absolute best hardware (for Oc'ing) in my opinion ever put out by Apple. If you have crappy soldering skills, here are some tips.

Add solder to the jumpers to remove them. Wrap the whole jumper in solder, as this facilitates heat transfer. On the first couple OC's that I did, I failed to do this, and ended up removing (by accident) the actual pads that the jumpers are soldered to right out of the mobo.

To test out different speeds, remove the faraday plate and the cd-drive, but keep everything else intact and in place. Plug in the power cord (to the inside of the case) and replace the case, then you can try out whatever configuration that you want without having to completely take apart the emac every time. Works wonderfully.

Any ways, see what happens, and let me know if you need any help.

Oops....

I forgot to give lbodnar MAAAADDDDDD props for all the info and the help. It is absolutely amazing and so helpful. I couldn't believe the results when I did my first OC, but it was real! I had done it myself!

Thanks again.

New

Hello all, and thanks for all the great work. I am a very basic solderer. I have gutted my 1.25ghz eMac due to a fried out analog board. Im trying to just run it headless for now to test it because it has a bad K capacitor I need to repair. I need to make the Logic Board power connector to connect to the ATX power supply but not quite sure howto go about doing it. I have read the diagrams but am not sure of the exact process. If anyone still reads this thread please can you help me make these? Thanks again for help in advanced. I can be reached through email just add @gmail to my name

Silly trick: route power button through modem port

For those clustering these or if you just want to avoid having to mount a separate switch, or if your power button connector broke off anyway, it is so damn easy to connect the power button leads to the rj11 jack for the obselete POTS modem, you could almost say it was designed that way Just make sure nobody plugs in a phone line -- maybe best to wire a pushbutton to an rj11 jack and glue it in there.

Sorry about the fuzzy photos, cell phone has an enragingly stupid focal length.



Other details:

Yes in case anyone was wondering a Gen3 1.25GHZ board will run with the CPU supply voltage at 5V (and the DCB still at 12V).

For a completely headless boot, attach a keyboard and ethernet cable, switch on PS (note blip on ethernet hub light then it goes back out), hit power switch (ethernet hub light comes on), quickly hold command-alt-O-F, wait for a off/on blip on the hub light or up to 90 seconds, then blind type:

dev /platform/telnet (hit enter)
" enet:telnet,XX.XX.XX.XX" io (hit enter)

...where XX.XX.XX.XX is a valid IP on your segment.

Note a 1/2 to 1 second blip on the ethernet hub light. That means it worked. Telnet to the IP address and you're in OpenFirmware where you can completely netboot linux with nfsroot.

Now I just need like 15 more of these things.

Thanks to everyone who hacked the hell out of this baby.

P.S. in answer to above post -- just go here:

http://www.lbodnar.dsl.pipex.com/eServer/

...leave the DCB attached to the logic board, make sure you have some ram installed, and just attach the leads as labeled underneath the first picture. Optionally for pins 5 and 7 use 5V instead of 12V. I used some old connectors from 3.5" floppies and reorganized the colors, crimped them a bit tighter, and twisted/taped all the colors into groups along with a male peripheral connector from an inline fan power splitter to plug in the PS. The wires are running a bit above their rated ampacity, but nothing's getting warm in there -- I would not try it with a motherboard MIDI connector, ribbon cables aren't meant for that.

Shave the connectors down to fit with a dremel or if your don't have that I hope you know how to whittle . The little LED on the other side of the board should come on when you turn on the power supply. I'd work with 150W+ AT PS to start, they are simpler to deal with.

Hi there.

I have arrived at this thread with an issue.

I have just inherited a 1Ghz eMac (one of the underclocked from factory units) off a friend who attempted to overclock his unit and in the process has caused the unit no longer to boot.

Having a closer look, the problem appears to be that he has removed far to many jumpers off the pcb around R270 and R275.

I have figured out the correct values (open or closed) for some of them using the earlier tables, but am struggling with some from the R270 row.

Would someone be able to to post or link a high res picture of that section of the board so I can get this great machine booting again.


Thanks

I been looking through this whole thread and I don't know if any of the cracks are still out there. however I got some questions hope someone is still listening.
A in one of the posts it is said that the solder pads on the side could be used for cpu jumpers. I see where the traces line up for the bottom pads in the picture http://www.lbodnar.dsl.pipex.com/eMac/eMac-jumpers-closeup.jpg except for the very bottom one there it seems to be reversed. The question is do they all share a common ground? (this is for the second generation) because I screwed up one of the top padsso I'm hoping this is a solution.

B. I have a generation 3 (1.25ghz) board coming (just have to replace the caps ) just the logic board mind you is it completly compatible with the second generation one? would be sweet to put that in my emac and run the other one headless

terramir

I figure I add up and sum up some info

the 3rd generation is a drop-in in the second gen board I can confirm that now albeit the 56k modem header is different so if you use a modem you'll need a different one, also the power header is on the otherside of the board in the same position so that is the only difference you need to know for repairs. The oc'ing info is in this tread but you have to dig for it posts 377 and 380 (there on page 16) have the info thanks lbodnar where ever you are for the info.
these macs are fast enough to run leopard although the 800 mhz and 700 and 800 from the first series have to be oc'ed to 867 minimum or you have tio run a patched install.
As for memory the second gen takes low density SDRAM and a max of 1gb
the third generation takes up to 2gb 2x1gb pc-2700 ddr (the apple website says 1gb but I'm running a 1gb stick in one slot right now so 2gb will work.
The dcb on the second and thrid generation are compatible however you could just run the board headless as well, Hint on headless installs you might want to use a CRT monitor first because that way you can just straight install most LCD's can't handle the refresh rates this board demands but a decent size CRT should be able too (remember it needs to be able to handle 1280x960 at 72 hz, 1152x864 at 80 hz and 1024x768@ 89 hz. the refresh rates are the problem once installed you can use switchres do force a custom resolution and your all set
terramir

Freezing Problem

Ever since i overclocked my 2nd Gen eMac from 1GHz to 1.266GHz, i've had an issue of constant freezing. I also tried it on 1.2 flat and on 1.33. I put it back at the 1Ghz speed, but it still likes to lock up on me. Did this happen to anyone else? I think my HD might also be the culprit!

Ok, I feel a little slow right now. I've read through this entire thing, but am not sure I saw the information I need.

I've already successfully overclocked my 3rd gen 1.25ghz eMac to 1.5ghz, but now I want to replace the crt with my 17" lcd.

Can anyone point me to the proper pinout for the power and video connectors on the logic board? Will I need to fabricate any additional electronics or will a standard ATX power supply work?

My last question is this: I know I will most likely require SwitchResX to get my main screen to the proper frequency. Everyone says to install VNC or other software to remotely log in. If I do a fresh install of Leopard before my mods, and set an external monitor to mirror the main, would I be able to see everything on the second screen to correct the resolution of the first, or will it be funky like the main and I will have to VNC or TeamViewer into the eMac anyway?

Any help I can get here will be very greatly appreciated, thanks!

lbodnar said:

All the pinouts were posted in this thread (or here http://www.lbodnar.dsl.pipex.com/eServer/). You can use standard ATX power supply.

If you preset mirroring and then boot up then you should be OK with external video connection but I think it do not work during bootup process (can't remember now) so it may be problematic to run different boot volumes or install/diagnostics CD.

By default internal video has a very high refresh rate (100Hz?) so unless you have a very capable TFT screen / HD TV connected you won't see anything until you drop the refresh rate on internal display.

Click to expand...

So then 2nd gen and 3rd gen are the same? Thanks Leo!!

Just wondering if someone could help me here? I have a 3rd gen emac that i want to run sans case. I have the thing apart, and have wired up the power connector thus:

http://www.nzlocal.com/simon/DSCF0975.JPG

Do i have this correct?

Thanks,

Simon

1.92GHz eMac 7447B

I got some update for this fantastic thread.

Recently I bought 1.42GHz eMac to overclock it. Thanks to Leo's great research I was able to do some new experiments.
First, I confirmed that 1.42 uses 7447B CPU (not A, like is stated in all sources). This is printed on die, as usual. Then came OC time

Started with 1.67 GHz and it was walk in the park. It went without troubles to 1.75 GHz. All with stock Vcore which is set to 1.325V. Stable as rock.
And finally, it came time for 1.92GHz. I've reminded that Daystar was offering 1.92 GHz upgrades based on 7447A, so I was sure that it's possible to reproduce with 7447B CPU. Bumped Vcore to 1.350 and it booted with 1.92 GHz. It was little unstable (some software unexpectly quit). So I made next step up with Vcore - to 1.375 - and it was enough for CPU to stay stable. I didn't test 1.83 GHz but if it runs at 1.92 why it would not run with lower clock.
Now I have 1.92 GHz eMac USB 2.0

Obviously, I reapplied thermal paste on CPU and GPU. I used IC Diamond Carat 7.

I've expanded Leo's multiplier table with 2 additional columns.



Here are screenshots:



Great thanks to lbodnar and other MR members, who posted in this thread, for sharing their knowledge here.

Now it's time for LCD mod and RAID 0 (or SSD) maybe.

Update:
It went to 2.0 GHz but wasn't stable, even at 1.425V. So I'm back to 1.92 GHz. That's max stable freq what I was able to reach with this computer.

greminn said:

Just wondering if someone could help me here? I have a 3rd gen emac that i want to run sans case. I have the thing apart, and have wired up the power connector thus:

http://www.nzlocal.com/simon/DSCF0975.JPG

Do i have this correct?

Thanks,

Simon

Click to expand...

I'm going to guess no, since you seem to have shorted pin 1 and 3, which are supported to be connected to the 12V lead.

dilbert4life said:

I have done this mod so many times, it isn't even funny any more. Just last week, I got a load of 12 1Ghz emac's in, and have over clocked all but 4 of them.

Most of the machines hit the 1.47Ghz mark very easily, and all it required was removing 2 jumpers from the 1Ghz configuration. I am really quite impressed. The machines went from getting 12 pts in Xbench 1.3 running 10.2.9 to getting nearly 40 pts (after the OC) under 10.4.11. Can't beat that, can you.

Anyone who has reserves about blowing up their computer for doing this, forget them. The eMac is the absolute best hardware (for Oc'ing) in my opinion ever put out by Apple. If you have crappy soldering skills, here are some tips.

Add solder to the jumpers to remove them. Wrap the whole jumper in solder, as this facilitates heat transfer. On the first couple OC's that I did, I failed to do this, and ended up removing (by accident) the actual pads that the jumpers are soldered to right out of the mobo.

To test out different speeds, remove the faraday plate and the cd-drive, but keep everything else intact and in place. Plug in the power cord (to the inside of the case) and replace the case, then you can try out whatever configuration that you want without having to completely take apart the emac every time. Works wonderfully.

Any ways, see what happens, and let me know if you need any help.

Click to expand...

I have an eMac 1GHz also and would like to try and oc it to 1.47GHz too, BUT the original multiplier chart in this thread only goes up to 1.4GHz and I was wondering if you could tell me what what two jumpers you are removing to obtain 1.47GHz (11x multiplier I am assuming)?

Here is the original chart, I have expanded on it adding the 1.47GHz speed that you have reached (circled in red). If you could just fill me in on which on the jumper config, thanks.

Man, props to you guys that are doing this. I've afraid to crack open my old eMac to replace its dead hard drive, much less do any of this stuff.

bobbytomorow said:

the original multiplier chart in this thread only goes up to 1.4GHz and I was wondering if you could tell me what what two jumpers you are removing to obtain 1.47GHz (11x multiplier I am assuming)?

Here is the original chart, I have expanded on it adding the 1.47GHz speed that you have reached (circled in red). If you could just fill me in on which on the jumper config, thanks.

Click to expand...

Ok I figured out the jumper config to obtain 1.47GHz (1.466GHz actual) and have expanded the chart accordingly.

Well since i assume this thread it semi-live again: which side is the "reverse side" and which side is the "J11 side." MrFX's website, which had all of these pictures, is no longer up, and i'm confused out of my mind. Also, I've overclocked a second gen eMac, but I need advice for a third gen: what is the recommended speed that is stable but doesn't require modifying the vcore? I'm thinking about going to 1.75 from 1.25... I know this thread is ancient, but you are all gods about this stuff.

Welp I wasn't stable @1.466GHz but I seem to be sitting pretty @1.4GHz, sweet A big thanks to lbodnar and everyone else in this thread.

Chance9888 said:

Well since i assume this thread it semi-live again: which side is the "reverse side" and which side is the "J11 side." MrFX's website, which had all of these pictures, is no longer up, and i'm confused out of my mind. Also, I've overclocked a second gen eMac, but I need advice for a third gen: what is the recommended speed that is stable but doesn't require modifying the vcore? I'm thinking about going to 1.75 from 1.25... I know this thread is ancient, but you are all gods about this stuff.

Click to expand...

By reverse side do you mean the other side, or backside, of the logic board? Or which way is up and which way is down for the jumpers? Because, I am just beginning here myself, but AFAIK you don't need to touch the other side of the logic board (backside), just the side facing you when your take out the optical drive.

And the jumpers are in red, from top to bottom, they correspond with the chart i posted.

bobbytomorow said:

Welp I wasn't stable @1.466GHz but I seem to be sitting pretty @1.4GHz, sweet A big thanks to lbodnar and everyone else in this thread.



By reverse side do you mean the other side, or backside, of the logic board? Or which way is up and which way is down for the jumpers? Because, I am just beginning here myself, but AFAIK you don't need to touch the other side of the logic board (backside), just the side facing you when your take out the optical drive.

And the jumpers are in red, from top to bottom, they correspond with the chart i posted.

Click to expand...

Hmm... Well, i'm about to crack open my third gen, right now. I just realized i can find the jumpers by the resistor number: Look in the chart posted above Here

Chance9888 said:

Hmm... Well, i'm about to crack open my third gen, right now. I just realized i can find the jumpers by the resistor number: Look in the chart posted above Here

Click to expand...

You're right, I just noticed that 3rd gen eMacs have jumpers located on both sides of the logic board, my mistake. Mine is a 2nd gen and all the jumpers are on the same side.

If it helps there is an image of the reverse side in this post.

For what its worth too I just used a #2 pencil to close the required jumpers, rather than solder, and it worked fine. To open them back up you can simply erase the pencil bridge...It saved a lot of time and mess

Thanks to all for EVERYTHING!!!

I have been messing around with my emac for quite some time now and i finally got it 100% dialed in. i started off with 1.25Ghz and now im running at 2.08Ghz. i cant tell you how this happened, but i overclocked it originally to 1.58Ghz with a .025 Vcore increase and fixed my "ATM" with the open firmware fix. i was having problems with my mouse freezing on wake-up from sleep and slow boot "gear" logos, so i decided to run these in open firmware:

reset-nvram
set-defaults
reset-all

once i booted back up the gear logo was spinning like a top and everything looked good. i opened up my "ATM" fearing the 750Mhz problem until it says 2.08Ghz. I did not believe this until i ran GeekBench and it came back with a score of 1167!!!! I know this is legit because a few days earlier after the overclock it scored a 835. look here at the full score http://browse.geekbench.ca/geekbench2/view/329447

i have also overclocked the graphics card with ATIcellerator II running just over 22% on both processor and memory values. The SMART sensor is reading 116.6 degrees fahrenheit and holding steady under load. The fan is a little loud, but i can deal with it since i can now watch youtube videos without viewing them frame by frame. does anyone know what may of happened with the clock?

Congrats! You have (by accident) the fastest eMac I've seen. You Geekbench score confirms that. My 1.92 GHz scored 1138 (slightly lower than yours): http://browse.geekbench.ca/geekbench2/view/276397
My guess is that you have soldered/desoldered wrong resistor.

2.08 GHz is unusual for 1.25 GHz CPU, because highest reported stable overclocks were @1.75 GHz.

I decided to register just so I could say how absolutely epic a 2.08GHz eMac is.

Must be zippy. I'd bet it wouldn't break much of a sweat playing ball with a Core Solo.

SSD! SSD! SSD!