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Louis918 · Jul 11, 2006, 09:17 PM

since the parts required for this mod have dropped in price...i can't resist pondering if it would work. i figure i could get a pismo logic board for about $20 and an onyx logic board for about $20 so here is my idea...

first, i was wondering if it is as easy as just exchanging the gpu chip and vram from one logic board to the other. i know what would be involved with the intricate soldering, but that wouldn't pose a problem with me. would the pin arrangement be interchangeable like that? what would the system do...just recognize the new gpu???

second, could i again, just switch the 550mhz G4 chip with the pismo's G3 chip? just really difficult soldering, but is that it?

let me know if it's possible or if it requires much more, like altering the power source and firmware. i'm considering this for fun and because i like my pismo.

Louis

Velocity211 · Jul 11, 2006, 11:42 PM

I could only dream of doing this, I have no idea if this would work but I'm thinking that it wouldn't. I always wanted a X1600 replacing my 9700. Just don't waste too much money on trying to do this.

Louis918 · Jul 12, 2006, 02:46 AM

Originally Posted by Velocity211

I could only dream of doing this, I have no idea if this would work but I'm thinking that it wouldn't. I always wanted a X1600 replacing my 9700. Just don't waste too much money on trying to do this.

i'm just trying to determine if an ati rage 128 with 8mb of vram could replace an ati radeon mobility x4agp with 16mb of vram...with no firmware modification.

i've read conflicting reports about these two cards and their vram. some have said the vram is built into the gpu and some say it's on the logic board. the ones that say it's on the logic board claim that the pismo is capable of excepting two equal blocks of memory...say 2&2, 4&4, or 8&8.

i didn't inspect my pismo's logic board when i had it disassembled, so i'm not sure, but even if thats true, could i take an 8mb ram chip from another pismo and double it up?

someone has to be an expert with these two chips, let me know!!!

Louis

Tuoder · Jul 13, 2006, 01:22 AM

I would imagine that the firmware for the G4 and G3 chips would be different, making a swap not work correctly. Also, I'd be worried about cooling, if it even worked.

baakre · Jul 16, 2006, 04:02 PM

FYI - I just got my Pismo CPU card upgraded to a G4 for about $60. The 7400/7410 G4 processors are pin compatible with the IBM G3 processors used on the Pismo. I received a "free" sample 500MHz G4 processor from Freescale, which I had installed on the Pismo CPU card. Since I did not have a good way of removing/installing BGA packages, I decided to ship it out to someone who could. I used a company called CC Electronx. I provided them with the CPU card and the bare processor, and they swapped the processor for about $60. Turn around time was about a week and a half.

I just got the cpu card back this weekend, so I guess time will tell how well this will work. I'm now enjoying video content from the itunes music store. I could never watch this before as the video and audio would studder so bad that it was unwatchable. This is by far the best $60 upgrade I've done in a while!

Originally Posted by Louis918

since the parts required for this mod have dropped in price...i can't resist pondering if it would work. i figure i could get a pismo logic board for about $20 and an onyx logic board for about $20 so here is my idea...

first, i was wondering if it is as easy as just exchanging the gpu chip and vram from one logic board to the other. i know what would be involved with the intricate soldering, but that wouldn't pose a problem with me. would the pin arrangement be interchangeable like that? what would the system do...just recognize the new gpu???

second, could i again, just switch the 550mhz G4 chip with the pismo's G3 chip? just really difficult soldering, but is that it?

let me know if it's possible or if it requires much more, like altering the power source and firmware. i'm considering this for fun and because i like my pismo.

Louis

skipjakk · Oct 4, 2006, 11:55 PM

Did you ever attempt this? I believe the Rage 128 mobility that came with the Pismo has 8mb on board, some of the later mobility chips that ATI made have 16mb on board. I didn't think the pismo had separate memory for the video, but I may be wrong. Let us know how this swapout goes!

Waragainstsleep · Oct 5, 2006, 01:56 PM

The 16MB is the Radeon from the G4 Onyx. Doubt they are pin compatible I'm afraid. On computers with onboard GPU and built in LCD, the LCD controller is sort of skipped out. (On a desktop, your GPU converts to DVI or VGA, then the external LCD converts back to a more proprietary pinout, specific to the LCD panel being used.)
Since the screens on G4s are a different format as well, its even less likely the two different GPUs are pin compatible. If they were, I suspect they would run under an identical very basic firmware driver until the correct driver for the GPU can be loaded up. You don't need to change firmware on a desktop when you swap the graphics card.

As for the CPU, they are as mentioned pin compatible (The early G4 is essentially a G3 with an Altivec unit bolted on). PLL settings for clock speeds and core voltages may vary, along with the speeds and voltages themselves.

skipjakk · Oct 5, 2006, 08:51 PM

What about the M4 (ATI mobility) I believe its pin compatible, and had 16mb on board?

Waragainstsleep · Oct 6, 2006, 01:34 PM

Not familiar with the M4. If it was used in a Mac and happens to be pin compatible, you get on fine with it. If it has never been used in any Macs, it won't have its own drivers for OS X.
To give a better example of my previous point, if you took the same GPU from an Apple notebook and a Dell, you are not guaranteed they will work if you swap them. They could be running entirely different LCDs.

You are more likely to have success swapping the VRAM. Again success will depend on the chip, but people have swapped flash chips in iPod Nanos and supposedly it works.

Pismo boards don;t cost so much these days. Maybe you could some super cheap, partially functional ones from somewhere. I had a few with no on board ATA for the hard drives. They would boot fine from firewire. Makes a risk free test rig. There's a few of them about which have suffered from this issue.

blackandblue · Nov 13, 2006, 04:19 AM

hey there, ive been given an old lombard, from what i understand from the interweb u can swap cpu cards with the pismo. Also if i read baakre's comments correctly i should be able to get the g3 cpu swapped out for a g4? ive got a 7400 g4 chip from a sawtooth, that i took out when i upgraded that to a quicksilver cpu. As this is a non mission critical machine id love to mess around with it, no great loss if it breaks. As for the freescale sample? hows does one get one of those? 550 would be nicer than 400. Anyhow hope you guys have some answers. Thanks