NVIDIA GeForce RTX 3090 and RTX 3060 GPUs Tested With Custom Memory BIOSes: Reduced VRAMs and Narrower Interfaces

While we’re right on the verge of the next generation of computer hardware, including CPUs and GPUs, fascinating events stemming from current-gen components are still plenty abound. Just hours ago, we learned that NVIDIA is planning a price-cut on RTX 3080 and RTX 3090 series graphics cards, and now, a new benchmark report has come forward, comparing different versions of the same RTX 3090 card.

PRO Hi-Tech, a Russian YouTube channel, got their hands on two custom BIOSes for the RTX 3090, both of which alter the card’s memory specifications. Not only that, but they also acquired a custom memory BIOS for the 3060, as well.

RTX 3090 with 20GB and 12GB custom BIOSes in CPU-Z | PRO Hi-Tech

This is actually one of the first software-based mods of its stature that we’ve seen for the RTX 30-series. Usually, extreme modifications are done via physical hardware, such as replacing the memory modules present on the PCB itself with faster or higher-capacity ones. 

RTX 3090 with custom memory BIOSes

Regardless, this is an interesting experiment as the custom BIOSes don’t actually make the GPU more performant—instead, they reduce it. PRO Hi-Tech test two different BIOSes that limit the size of the memory and the bandwidth. The first custom BIOS offers 20GB of memory running across a 320-bit wide interface. Whereas, the other custom BIOS reduced the memory size to 12GB across a 192-bit memory bus.

Keep in mind, the RTX 3090 actually comes with 24GB of memory out of the box. Memory speeds on both custom BIOSes are untouched at 21Gbps, but due to the narrower interfaces, both see different fallouts in their overall bandwidth. The original memory bandwidth for the RTX 3090 is 936GB/s, but the custom BIOSes take that number down to 780GB/s and 468GB/s, respectively.

Both BIOSes were tested across a bunch of games and put through 3DMark‘s Time Spy and Port Royal benchmarks. Speaking of Time Spy, the 24GB RTX 3090 nets 18,388 points, while the 20GB custom BIOS model achieves a score of 17,686 points. A more drastic difference is experienced with the 12GB model that only gets 13,996 points in the same test; a 24% decrease over the original’s (24GB) performance.

RTX 3090 24GB vs. RTX 3090s with custom 20GB and 12GB BIOSes | PRO Hi-Tech

The 12GB custom BIOS severely hinders the RTX 3090’s potential. We see a loss in performance of up to 76–85% with it, while the 20GB model barely performs about 5% worse than the original. This could be the reason as to why NVIDIA didn’t bother with the rumored RTX 3080 20GB model last year, since it would bring forth such a gigantic improvement in performance over the originals that it wouldn’t make sense.

RTX 3060 with custom memory BIOS

Moving on to the RTX 3060, PRO Hi-Tech also tested the mid-ranger with a custom BIOS that disables 4GB of memory. The original RTX 3060 features 12GB of memory running across a 192-bit wide bus, but the custom BIOS limits that to just 8GB across 128-bit. Long story short, the custom BIOS performs about 18% worse than the original in games.

However, since disabling 4GB of memory essentially turns off two memory modules on the PCB (Ampere GPUs use 2GB VRAM chips), that results in reduced power consumption. 

PRO Hi-Tech did not provide any sources or links to get the custom BIOSes but, to be fair, you don’t need them anyways. You can check out their video below, though it’s in Russian and does not have English subtitles.

Huzaifa Haroon
Born and raised around computers, Huzaifa is an avid gamer and a Windows enthusiast. When he's not solving the mysteries of technology, you can find him writing about operating systems, striving to inform the curious.