RX 9070 XT Noctua mod V.3 - Improved thermals at low RPM
Haven't posted here before, but basically this is a newest revision on my series of making Noctua mods for my Gigabyte RX 9070 XT Gaming OC. You can check my earlier posts for more context.
This shroud can accept any standard 120mm PC fan, but flow guide between fans and heatsink is fitted specifically to Noctua NF-A12 fans.
Problem with earlier revision was that fans were flush against the heatsink, leaving a section between them that received zero flow. To solve this I offset the fans and added an guide to spread out the flow to cover the whole heatsink. I was also hoping that the expanding flow channel would improve static pressure and push more air through heatsink with the same RPM.
Since the fans are ~11mm wider than the heatsink, I also added a ramp over the fan overhang to redirect all the flow back.
Shroud includes a flow splitter on the bottom. It separates flow from the bottom fans, preventing hot air recirculation and helps push hot exhaust air behind GPU towards case roof.
Video about shroud for those wanting more context: https://www.youtube.com/watch?v=QeNS42-2hp0
Setup
Lian li LANCOON 216 (front fans 650 RPM)
be quiet! Pure Loop 2 FX 360 (radiator fans 1120 RPM)
2xArctic P14 Pro fans (under GPU supplying air, 815 RPM)
Gigabyte RX 9070 XT Gaming OC, Noctua 120mm G2 fan speeds stated per test
Room temp 24C +-0.5C in all tests
Check the pictures for test results. Basically below 1400 RPM (80%) fan speed I gain 2-3C cooling performance (lower RPM - higher delta) compared to V.2. Meaning V.3 is more efficient.
Difference might seem marginal, but comparing to my early testing without a shroud (fans ziptied to heatsink) and accounting for different room temperatures between tests, I have improved overall GPU temperature around ~6C with the shroud alone at same RPM.
Note that these are synthetic benchmark temps, under typical gaming load temps are few degrees lower.
Noise profile is pretty identical to V.2, but since my (somewhat arbitrary) goal is to keep hotspot and VRAM under 90C at stock setting during sustained load, I could comfortably lower my fan GPU fan speed around 1000 RPM, extremely silent with Noctua G2 fans.
System noise is mostly limited by case and CPU fans, since I couldn't measure meaningful difference with GPU fans off or at 1000 RPM (around 31.5 dB 40 cm away), guess I'll have to start replacing my case fans if I want the system any more silent.