I went in the test with those expectations as well. When testing Toughfan 12 and A12x15 on a radiator outside the case it seemed that there was no contest. Both at full speed, Toughfan 12 had noticeably more airflow and was probably a bit quieter. I was too puzzled by the result.
So I tested these two setups:
Three A12x15s on the top radiator (elevated by 6mm w/ these, which results in 1 °C improvement than not elevated as tested previously).
Two Thermaltake Toughfan 12 (aka "pre-release" Noctua A12x25 chromax) on the top radiator (pull) + one A12x15 (push). I did not...
So in my dual-rad setup I tested not having these 6mm worth of washers. It's 1 C worse in coolant temp without them. Top & side radiator fans @ 1200rpm, 380W load.
This is in preparation for testing Thermaltake's Toughfan 12, since it's unclear when Noctua A12x25 chromax will come out.
I concur with the comments against removing the short fan bracket. It would make the build much more difficult and less clean.
Which strut on the motherboard side is being removed? Is it one of the struts the radiator is mounted on or the one the PSU is partially mounted on?
Some have reported turbulence noise when the fans are below the radiator. It might be best to have them on top. It would also help if you route the tubes away from the fans/radiator as much as possible, but I'm not sure how feasible it is.
Blackened my build (swapped tubes, PSU fan, and Hanjiang side radiator to black version).
In case you haven't seen them there are results here and here. I think Hanjiang will do better when noise normalized, simply because Noctua A12x25 runs several hundred more RPMs than A12x15 at the same...
Have you tried taking it apart? I was able to fix one of them by removing the end tank and cleaning up a small piece of debris that was caught between the o-ring and the housing. Hanjiang also suggested to me to sand the housing piece (the opposing surface of the o-rings).
In case anyone is interested in the Hanjiang 17mm radiator, I bought another two with black fins. Both of them leaked! I was able to fix them but they asked me to not talk about it. Of course I’m going to talk about it. They really need to do a 3-min leak test before they ship.
Well, with the right dual-rad configuration (super small GPU footprint, e.g. 3080 FE with deshrouded Corsair block) it does perform similarly or even outperform dual-rad M1. Compare results below (GPU @ 56 C with ambient @ 21.8 C, fans @ ~920rpm, 3080 undervolted to 250W, i.e. comparable to 2080...
They do have 120x17 and 360x17 as well. The 120 also comes in black now.
Unrelated, I just tested sanded (11.75mm) vs stock A12x15 as exhaust on Hanjiang on the side. The sanded setup was about 1.5 C better in coolant delta running at the same fan speeds. I measured noise as well and there was...