An Asus ROG Astral LC RTX 5090 has been shunt modded, resulting in its performance eclipsing the $10,000 RTX Pro 6000. This kind of PCB surgery mod is notorious for resulting in damaged graphics cards, so please monkey-see monkey-do with extreme caution. However, the video of this particular feat was put together by overclocking legend Der8auer, so everything went extremely smoothly and to plan. Below, we will ponder over the process, the results, and consider whether the work and risks are worth it.
Shunt mod – a procedure to increase the hardware power limit
As briefly mentioned above, shunt modding can be dangerous to the life of your GPU. If mistakes are made, your $$$ GPU could degrade slowly, or become toast extremely quickly. As well as any concerns about the actual mod to the PCB, remember that any strain on the 16-pin power connector could become even more perilously high at 800W.
A great shunt mod candidate
Der8auer told viewers that he waited until he could get a capable AiO card for this shunt mod experiment, as it should be better at handling the greater power. And indeed, the Asus ROG Astral LC RTX 5090 runs quieter than the ‘vanilla’ Astral, according to the overclocker. All else being equal, the Astral cards offer a welcome degree of parameter adjustment and monitoring options via Asus GPU Tweak III – this will be useful later.
First things first, Der8auer set a baseline for out-of-the-box Astral LC RTX 5090 performance. During this initial assessment, he observed that it was hitting the standard 600W power target constantly when under load, but seemed “pretty quiet” and capable of handling more juice. It was concluded by the OC expert that the 600W limit was definitely reducing OC potential.
Now the decision had been made and baselines recorded – it was time to crack open the LC and mod the PCB. We won’t get into the details of how to shunt mod, but you can see an overview of the procedure in the video embedded above. But in brief, the mod is rather straightforward. It simply requires changes to be made to the resistors coming from the power connector to ‘fool’ the controlling circuitry into thinking less power is coming in to the PCB than there actually is... With the resistor replacements Der8auer chose, the mod would allow “us in theory to get about 30% higher power draw without the card noticing.” Thus, a separate piece of hardware, called WireView, would be used to see the actual power draw. In the case of the Astral cards, you also have pin sensing on the 16-pin power input, so that is another view of the incoming power that is available, and should remain useful.
Results and conclusion
The mod went well, and WireView reported about 660 to 700W being used under modest benchmark loads. That contrasts with the GPU-Z readout of around 500W. It was also observed that there was 15 to 20% more headroom left until the new power limit would be hit.
During fresh benchmarks, the CPU only occasionally ran into the new power limit; most of the time, it seems to be at around 750W during the tests. Then it was decided to delve into manual overclocking, with acceptable temperatures and noise levels continuing.
To conclude, the shunt-modded RTX 5090 beats the $10,000 RTX Pro 6000, but only just. You can also see an alarmingly higher power consumption vs both the unmodded RTX 5090 and the professional graphics card with its 96GB VRAM. Der8auer was pleased and called the result “quite nice.” However, we think it is worth underlining our earlier comments about the dangers of doing a shunt mod on expensive graphics cards.
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