Is it possible to upgrade vram on Imac Duo

[munkees]

I was wondering if anybody knows if the iMac Duo is GVram is upgradeable after purchase, is it a socket ram or solder.
for example 128 to 256 or even 512 ?

 

[robbieduncan]

No. In general the only way to increase the amount of graphics RAM in ANY modern computer is via a new graphics card (I realise back in the dawn of acclerated 3d cards shipped with sockets for more RAM, this has not been common for at least 6 years). As the iMac does not have a card but the graphics chip and VRAM is soldered to the logic board you are out of luck.

Edit to add: even if it was socketed you would struggle to get the RAM. VRAM tends to be faster/different spec to normal RAM anyway.

 

[munkees]

But it must be possible to purchase the chips and soldier them on, if you know what you are doing ? I guess the only way to know how is to look at the 128 and the 256 next to each other and see what chips are missing and what else is required like other smaller resistors etc.

Too much work, for me

 

[robbieduncan]

But it must be possible to purchase the chips and soldier them on, if you know what you are doing ? I guess the only way to know how is to look at the 128 and the 256 next to each other and see what chips are missing and what else is required like other smaller resistors etc.

Too much work, for me

Solder them to where? There are not likely to be solder pads just waiting for the chips. Also they are surface mount so not really solderable by a person.

 

[mmmcheese]

Solder them to where? There are not likely to be solder pads just waiting for the chips. Also they are surface mount so not really solderable by a person.

I expect that there would be pads for the RAM because I highly doubt that Apple has 2 different logic board designs for the iMac. There are some people who are good at soldering and can do surface mount soldering, but most people even botch "simple" PCB soldering. The part that will most likely cause the most problems for adventurous hackers is that the RAM is most likely using the ball-grid-array format.

Wikipedia about BGA

A ball grid array is a type of surface-mount packaging used for integrated circuits. It is descended from the pin grid array (PGA), which is a package with one face covered (or partly covered) with pins in a grid pattern. These pins are used to conduct electrical signals from the integrated circuit to the printed circuit board (PCB) it is placed on. In a BGA, the pins are replaced by balls of solder stuck to the bottom of the package. The device is placed on a PCB that carries copper pads in a pattern that matches the solder balls. The assembly is then heated, either in a reflow oven or by an infrared heater, causing the solder balls to melt. Surface tension causes the molten solder to hold the package in alignment with the circuit board, at the correct separation distance, while the solder cools and solidifies. The composition of the solder alloy and the soldering temperature are carefully chosen so that the solder does not completely melt, but stays semi-liquid, allowing each ball to stay separate from its neighbours.

 

[robbieduncan]

I expect that there would be pads for the RAM because I highly doubt that Apple has 2 different logic board designs for the iMac.

My thoughts were that they would be using higher density chips for the larger VRAM thus keeping the number of chips on each board the same.

 

[mmmcheese]

My thoughts were that they would be using higher density chips for the larger VRAM thus keeping the number of chips on each board the same.

That's always a possibility, but I think that's the least of the worries. If you really wanted to, you could probably get your hands on different memory chips to replace the lower density ones (assuming they are).

 

[CANEHDN]

My understanding is it's the same board and chip set. All though Apple stores are not able to upgrade the VRAM. They say only Apple Online can do it. That may be the reason, if the boards are different.

 

[topgunn]

It is possible that all boards ship with 256MB and they have disabled 128MB. I guess it would depend on which was cheaper; making all boards with an extra 128MB of VRAM, the cost of labor to add 128MB of VRAM, or to have two different logic boards.

 

[tjwett]

It is possible that all boards ship with 256MB and they have disabled 128MB. I guess it would depend on which was cheaper; making all boards with an extra 128MB of VRAM, the cost of labor to add 128MB of VRAM, or to have two different logic boards.

interesting. after all, apple had been over and under clocking the G4 for like 5 years to make segments in the product line.

 

[Mechcozmo]

interesting. after all, apple had been over and under clocking the G4 for like 5 years to make segments in the product line.

Not quite... the eMac is the only really big exception, (along with the Mac Mini I suppose) but overall you can't get a huge performance boost out of a G4 by a quick solder job. Maybe you could get a few extra MHz, but the more likely chance is that you won't because the chip is stable at that speed and won't go higher.

Chips are made for a certain speed, say, 1.5 GHz for the G4s. But if they fail to hit 1.5 GHz, they are dropped to 1.33 GHz. If they fail that, 1 GHz. That way, you get all the chips you need from one line. If you need more 1 GHz chips, divert some 1.33 or 1.5 chips to that, and that's where overclocking chips lie.

 

[tjwett]

Not quite... the eMac is the only really big exception, (along with the Mac Mini I suppose) but overall you can't get a huge performance boost out of a G4 by a quick solder job. Maybe you could get a few extra MHz, but the more likely chance is that you won't because the chip is stable at that speed and won't go higher.

Chips are made for a certain speed, say, 1.5 GHz for the G4s. But if they fail to hit 1.5 GHz, they are dropped to 1.33 GHz. If they fail that, 1 GHz. That way, you get all the chips you need from one line. If you need more 1 GHz chips, divert some 1.33 or 1.5 chips to that, and that's where overclocking chips lie.

right, i meant more that they were underclocking the faster chips to put into the consumer stuff.