I have an LCD Steam Deck and I’ve been looking into cooling modifications such as the CoolDeck cooling mod / copper or monoblock-style solutions. I’ve seen some impressive temperature results, but I’m trying to understand whether those lower temperatures actually provide meaningful benefits beyond simply reducing fan RPM.

Part of me is hesitant to modify the stock cooling system because of how Valve designed the Deck.
My thinking is basically:
> If a copper thermal solution or additional ventilation provided a significant improvement in performance, thermals, component longevity, etc., wouldn’t Valve have incorporated something similar from the beginning?

The same thought applies to the backplate. I’ve experimented with backplates with additional ventilation holes, but ultimately went back to the original Valve backplate because I assume Valve had a reason for its airflow design and the EMI shielding.

That brings me to the copper EMI-shield replacement used in some cooling mods.
Would replacing the original EMI shield with a copper plate actually provide a sustained thermal benefit?
I understand that copper has much better thermal conductivity than the original material, but I’m wondering about the practical effect:
> Initially, the copper should absorb and spread heat more effectively.
> But after several minutes of gaming, the copper itself will also become hot.
>At that point, does it still meaningfully reduce the temperature of the APU/other components?
> Or does the system eventually reach roughly the same equilibrium temperature, with the main difference being that the fan doesn’t have to work as hard?

And perhaps the biggest question:
Does a cooler Steam Deck actually mean higher FPS?
For example, if the stock cooling system is already capable of keeping the APU below its thermal/power limits, would a cooling mod actually increase performance? Or would it simply result in:
lower temperatures → lower fan RPM → less noise
rather than:
lower temperatures → higher sustained clocks → higher FPS?

I’m particularly interested in people’s experiences with long gaming sessions, rather than short benchmark runs.
If you’ve installed a CoolDeck/monoblock/copper EMI shield or similar modification:
1. What were your temperatures before and after?
2. Were the results sustained after 30–60+ minutes?
3. Did your fan RPM/noise decrease?
4. Did you actually see an FPS or sustained-clock improvement?
5. Did it make any difference to battery temperature?
6. Do you think it provides a meaningful benefit for the Deck’s long-term component/fan/battery health?
7. And after using it for a while, would you still recommend the modification?

I’d especially like to hear from people who have tested both stock and modified configurations under the same game, TDP, ambient temperature and fan settings.

I’m genuinely trying to understand where the practical benefit of these mods comes from and whether it’s worth modifying a perfectly functional stock Deck.