u/akarenn

Hey everyone, I'm having a pretty serious issue with my 2025 Zephyrus G16 (GU605CX, RTX 5090 / Core Ultra 9 285H) and I'm wondering if anyone has experienced something similar.

Everything was working normally until yesterday while I was playing Tekken 8. Suddenly the game started running almost in slow motion. Since then, basically every game has been extremely slow.

HWiNFO while running Tekken shows:

• GPU usage: ~98%

• GPU temperature: 92.3°C

• GPU thermal limit: 87°C

• GPU clock: 277 MHz

• GPU effective clock: ~277 MHz

• GPU power: only ~42W

• FPS: ~14–15

The GPU fan is definitely working. HWiNFO shows it reaching around 5,000 RPM while Tekken is running (CPU fan ~5,400 RPM).

The CPU seems fine. CPU package temperature was around 77–78°C, maximum ~85°C, and HWiNFO reports no CPU thermal throttling.

At idle the RTX 5090 has also been unusually hot, fluctuating around 70–85°C, although I've been using dGPU/Ultimate mode so I'm aware that can increase idle power/temperature.

There's another strange problem that started at the same time. If I try to boot the laptop with the charger connected, it sometimes reaches the ASUS logo and then completely shuts off. If I unplug the charger, I can boot into Windows normally, and then reconnect the charger afterward and it appears to charge normally.

I also tried running the ASUS/MyASUS hardware diagnostic and the laptop completely shut itself off during the diagnostic.

So as of now I've confirmed:

• GPU fan is working

• CPU fan is working

• CPU isn't thermal throttling

• GPU is hitting/exceeding its 87°C thermal limit

• GPU clocks can collapse to ~277 MHz under load

• Gaming performance and FPS is super low when this happens

• Problem also occurs on battery (performance is still extremely poor)

• Laptop sometimes shuts down during boot when AC is connected

• Laptop shut down during ASUS hardware diagnostics

I'm wondering if this could be a heatsink/thermal interface/vapor chamber issue, power delivery issue, or something else hardware-related.

Has anyone with a 2025 G16, especially the RTX 5090 model, experienced anything similar?

I'm in Japan and will probably contact ASUS for warranty service, but I'd really appreciate any suggestions for things I can safely check or try myself first.

Right now I found a new Legion Go 2 Z2E 32GB 1TB for around 1250 USD. Should I go for it, or should I just go and buy a used Legion Go 1 for a few hundred bucks?

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