$142 Upgrade Kit and Spare Modules Turn Nvidia Rtx 4090 24gb to 48gb AI Card

Posted4 months agoActive4 months ago

RachelF

49 points

11 comments

tomshardware.comTechstory

calmmixed

Debate

30/100

GPU ModificationNvidia Rtx 4090AI Hardware

Key topics

GPU Modification

Nvidia Rtx 4090

AI Hardware

A $142 upgrade kit can modify an Nvidia RTX 4090 24GB to a 48GB AI card, sparking discussion on the technical feasibility, market segmentation, and potential applications of such modifications.

Snapshot generated from the HN discussion

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01Story posted
Sep 10, 2025 at 8:51 PM EDT
4 months ago
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Sep 12, 2025 at 2:25 AM EDT
4 months ago
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Discussion (11 comments)

Showing 11 comments

mdaniel

4 months ago

1 reply

> Clearly, this operation requires specialized soldering skills and access to appropriate high-end tools. [...] The technician also uploaded a leaked, modified firmware onto the GeForce RTX 4090 48GB. It is important to note that each graphics card possesses a unique GPU device ID, which contains all pertinent information. During the system initialization process, the firmware verifies whether the GPU device ID corresponds with the one embedded within the chip. Hacked firmware has been present for some time.

So, an interesting YouTube video, but the $142 is not the whole story here, both in terms of materials and way no in terms of wall clock time required

I appreciate that they did call out the total cost later in the article, along with re-mentioning the specialized tools and experience, but the headline here deserved extra "clickbait alert" call out

gorbypark

4 months ago

Especially since the $142 price doesn't even include the memory chips! The YouTuber had access to defective donor cards to pull memory modules from, so they hand wave that into being free.

metadat

4 months ago

3 replies

Why only 2x the ram? Wouldn't 96GB be even more optimum?

Pretty awesome people went to the trouble to do this, casts some light on what is typically darkness on the consumer side of GPU product market segmentation.

Capitalism wins every time.

londons_explore

4 months ago

1 reply

I assume because you need to have a stolen firmware image to load on.

Bet the ram size is a compile time constant and therefore you need to get hold of firmware from a card with the amount of ram you intend to add.

metadat

4 months ago

1 reply

Is it possible to extract the firmware and instead modify the blob? Or is the NV firmware cryptographically encrypted to disable such methods of tampering?

londons_explore

4 months ago

Even if you could modify the firmware, the RAM size being a compile time constant means it probably affects the memory map, all kinds of cache layouts, etc.

numpad0

4 months ago

2 replies

Devices on a bus architecture like RAM buses can be wired completely parallel to the same pins on the same bus master(i.e. DRAM controller), with only one separate chip select lines each. The address/data lines will not conflict so long that the component expected to speak/listen can be explicitly specified(there are other ways to specify as well).

GPU cores used in these double RAM NVIDIA GPUs are known to have that feature implemented and configurable in signed VBIOS, for some reasons. It only allows single or double RAM configurations as choices, not e.g. 4 separate lines for quadruple RAM, but double configurations can be done with a properly built and assembled PCB if you can source the cores. And there are tons of back alley trained skilled BGA repair specialists in China for mysterious reasons, so that's what they're doing.

hulitu

4 months ago

> And there are tons of back alley trained BGA repair specialists in China for mysterious reasons

In some countries it is cheaper to repair a phone than to buy a new one. This creates the "back alley trained BGA repair specialists".

When i was first employed in a Eastern Europe country, our computer supplier will "repair" RAM modules this way. Test was simple: insert in PC, see if it boots. It was the only place where i saw Windows 2000 crash more than Windows Me.

metadat

4 months ago

Could it be because some of the hardware in the 4090 overlaps with the Hopper (H100) architecture?

If so, I imagine NV "fixed" this oversight with Grace Blackwell -based GPUs (5xxx series). There is too much at stake financially to leave the barn door open.

Could you nvlink several 4090s?

adgjlsfhk1

4 months ago

space. there's a limited number of spots on the board for VRAM chips and a maximum capacity at current tech levels.

Cheer2171

4 months ago

Anyone have experiences with the 2080 22gb mods?

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ID: 45206302Type: storyLast synced: 11/20/2025, 4:50:34 PM

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