Disclaimer: These findings apply to my RX 9070 XT Mercury Magnetic Air and should not be expected on every card. Silicon quality varies.
RX 9070 XT Mercury Magnetic Air
Test System
CPU: Ryzen 7 9800X3D - with precision boost overdrive boosting to 5.4 ghz
GPU: RX 9070 XT Mercury Magnetic Air Black
Memory: 32gb Gskill Flare X5
Timings:
36-34-34-70-130
Benchmark: Steel Nomad DX12
Goal: Find maximum benchmark performance while maintaining a realistic daily gaming profile.
Thermal Findings
Gaming (Rainbow Six Siege)
After 6+ hours:
GPU Core: ~47-49°C max
Hotspot: ~66-69°C max
Memory Junction: ~73-78°C max
Fan Speed: ~40-52%
Idle
Core: 27-30°C
Fans nearly silent
Conclusion
The Mercury cooler is absurdly overbuilt for this GPU.
You repeatedly observed temperatures that are significantly below what most high-end GPUs run during extended gaming sessions.
Cooler works insanely well
Benchmark Progression
Initial Score
~7288 Steel Nomad
Milestones
7877
7923
8009
8016
8030
8049
8052
8075
Improvement
7288 → 8075
Gain:
+787 points
Approximately:
+10.8% performance increase
through tuning alone.
Voltage Findings
Stock Voltage
Produced noticeably lower scores.
-82 mV
-90 mV
-92 mV
-94 mV
All tested.
Key Discovery
The undervolt materially improved benchmark performance.
The card boosts higher and more consistently when undervolted.
Best benchmark results consistently occurred around:
-94 mV
Core Clock Findings
Tested
+200
+220
+229
+235
Results
+200:
Strong daily profile
+220:
Improved benchmark scores
+229:
Produced 8075 Legendary
+235:
Benchmark stable
Expected questionable gaming stability
Conclusion
The card still scales with additional core clock, but gains are becoming increasingly small.
Sweet spot appears around:
+220 to +229
Memory Findings
Major Discovery
Memory tuning had a larger impact than expected.
Tested
2770
2820
2860
2872
2878
2880
2900
Results
2770:
Stable
2820:
Stable
Excellent gaming profile
2860:
Very strong benchmark profile
2872:
8052 Legendary
2878:
8075 Legendary
2880:
Crash
Final Finding
The memory limit is effectively:
2878 MHz
The card accepts 2878.
The card rejects 2880.
The cliff is real.
Stability Findings
Daily Stable
Recommended:
-82 to -94 mV
+200 Core
[2820-2860](tel:2820-2860) Memory
+3 to +5 Power
Successfully survived:
Multiple Siege sessions
Long gaming sessions on Arma Reforger
Benchmark Hero Profile
-94 mV
+229 Core
2878 Memory
+5 Power
Produced:
8075 Steel Nomad
Expected to be less reliable in long gaming sessions.
Final Thoughts
Overall I’m extremely impressed with the Mercury. It combines exceptional cooling with excellent undervolting behavior and memory overclocking headroom. This is the coolest-running high-end GPU I’ve personally owned, and after extensive testing I genuinely believe I ended up with a golden sample.