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pi-tastic
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Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 7:38 pm

has anyone done this yet?
just curious.
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jamesh
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 7:54 pm

This is not as simple as simply adding a new chip to the board, although that is indeed quite difficult anyway, but you will need to update the bootloader with the new sdram timings.

And of course you will need to find a pin compatible DRAM chip...
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buja
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 8:07 pm

So, what's the problem :lol:

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davidcoton
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 8:21 pm

jamesh wrote:
Mon Aug 19, 2019 7:54 pm
This is not as simple as simply adding a new chip to the board, although that is indeed quite difficult anyway, but you will need to update the bootloader with the new sdram timings.

And of course you will need to find a pin compatible DRAM chip...
So, if its that easy, why hasn't it been done yet? :lol: :roll:
I'm sure @pi-tastic will have a go in the next week and let us know what happened (Hint: dead Pi). :geek:
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takyon
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 8:44 pm

16 GB doesn't exist. Not sure about 12 GB LPDDR4. Also consider 6 GB.

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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 8:46 pm

"...curiosity killed the RPi4B1G..." will be the next topic :mrgreen:
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Come to me with 'problems' and I'll help you find solutions"

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pi-tastic
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 9:02 pm

one could invest a little in the bga template and offer the service, mod the firmware, the question is, when one does an rpi-update will it brick?
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trejan
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 9:27 pm

pi-tastic wrote:
Mon Aug 19, 2019 9:02 pm
one could invest a little in the bga template and offer the service, mod the firmware, the question is, when one does an rpi-update will it brick?
You're still missing the most important fact that there are no compatible 8GB/64Gb parts. It has to be LPDDR4 and with the same 200 pin BGA package.

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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 9:40 pm

If it was so easy, why not plug in a 1 Terrabyte SSD drive in the ramport? ;)

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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Mon Aug 19, 2019 11:59 pm

What particular purpose does this idea serve?
Admittedly I asked a simar question about the Pi3A+, but that only has half a GB of RAM whereas a Pi4b has 2GB and 4GB options which should be more than enough RAM for sane usage. Adding more RAM won't get it to run the latest AAA x86-based game.
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bomblord
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 1:30 am

Good luck with that soldering job my dude. If you succeed I'll be in awe.

cjan
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 3:09 am

goto hua-pei-chiang, China.

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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 1:52 pm

bomblord wrote:
Tue Aug 20, 2019 1:30 am
Good luck with that soldering job my dude. If you succeed I'll be in awe.
With the right equipment it's not that hard to de-solder and replace BGA components.

Been mentioned before that there are limited choices of footprint compatible parts.
It's um...uh...well it's kinda like...and it's got a bit of...

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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 2:28 pm

Imperf3kt wrote:
Mon Aug 19, 2019 11:59 pm
What particular purpose does this idea serve?
Admittedly I asked a simar question about the Pi3A+, but that only has half a GB of RAM whereas a Pi4b has 2GB and 4GB options which should be more than enough RAM for sane usage. Adding more RAM won't get it to run the latest AAA x86-based game.
There are at least a couple of reasons. The first one is the same as that given for climbing very tall mountains: Because it is there. If the DRAM chips exist--now or in the future--someone will want to put one on a Pi simply because it exists. As you note, 4GB is enough DRAM for "sane usage". That doesn't prevent anyone from coming up with an insane usage, or--as in the first case--simply looking for a use that requires more DRAM than any Pi comes with.

I'm not saying these are *strong* reasons for the attempt, merely that they are reasons.

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pi-tastic
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 3:12 pm

i just bumped my 3B+ from 100m swap to 2000m and its, OMG so better to use. Chromium Gobbles up the ram and then stalls the machine not much after 3/4 tabs @ 100m swap.

Yeah I have no issues with BGA packages. Though I would not attempt it with out the proper stencil.

according to the official raspberry pi 4b video, compatible 8g and 16g chips exist, its just the price is up there.
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trejan
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 3:22 pm

pi-tastic wrote:
Tue Aug 20, 2019 3:12 pm
according to the official raspberry pi 4b video, compatible 8g and 16g chips exist, its just the price is up there.
Where does it say that? I've looked at all the major manufacturers and none of them list a 8GB or 16GB part that is LPDDR4 and has the same package + pinout.

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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 4:17 pm

trejan wrote:
Tue Aug 20, 2019 3:22 pm
pi-tastic wrote:
Tue Aug 20, 2019 3:12 pm
according to the official raspberry pi 4b video, compatible 8g and 16g chips exist, its just the price is up there.
Where does it say that? I've looked at all the major manufacturers and none of them list a 8GB or 16GB part that is LPDDR4 and has the same package + pinout.
If the pinout is different, would a carrier board be possible?

Image

It seems the days of stacking RAM chips with one select pin bent out are long gone.

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PeterO
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 4:28 pm

ejolson wrote:
Tue Aug 20, 2019 4:17 pm
trejan wrote:
Tue Aug 20, 2019 3:22 pm
pi-tastic wrote:
Tue Aug 20, 2019 3:12 pm
according to the official raspberry pi 4b video, compatible 8g and 16g chips exist, its just the price is up there.
Where does it say that? I've looked at all the major manufacturers and none of them list a 8GB or 16GB part that is LPDDR4 and has the same package + pinout.
If the pinout is different, would a carrier board be possible?

Image

It seems the days of stacking RAM chips with one select pin bent out are long gone.
AH , a "RAM Sandwich" . Last time I made one of them was with 8 x 6116s (8 x 2Kb static RAM).
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trejan
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Re: Modding 1gig PI4B, with 8gb or 16gig ram chip

Tue Aug 20, 2019 5:58 pm

ejolson wrote:
Tue Aug 20, 2019 4:17 pm
If the pinout is different, would a carrier board be possible?
I don't think so. The extra pins are for more channels. It wouldn't be fun to make with the high speed signals present anyway. $10 double sided prototyping PCBs from China aren't going to be good enough.

I don't consider this to be a viable option for reasons you'll see but the closest "active" part is MT53D2048M32D8QD-053WT which is 8GB x32 LPDDR4 in what appears to be a 200 pin BGA package but slightly thicker due to the additional dies. I say "active" because it has a 6+ month lead time so there are doubts about it actually being in production. The other major issue is that they cost £139 each and you need to buy a tray of 2000.

£173 for an 8GB Pi 4 isn't worth it especially since you still need to patch the closed source bootloader and there is no public datasheet to confirm the specifications of the RAM or how to configure the memory controller. If an 8GB Pi 4 appears then it'll be from Raspberry Pi themselves. Unlikely however due to the price of the RAM. Good luck to anybody crazy enough to want to DIY one. Maybe you can get a sample from Micron.

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