Air-cooling Ryzen 3900X in a Louqe Ghost

Sat 11 Apr 2020, 18:45

For a couple of weeks now I've ran a Ryzen 3900X in my Louqe Ghost S1 case.

12 cores in a case that small could be considered crazy, but it isn't too bad.

I was going to make this post a really long one, similar to the one I wrote last summer, and I started writing it, but it got too long and I got distracted and put it off. With that said, you should read my previous post about the case as a lot of info about the cooler and such are still relevant. Consider this post a sequel. You'll be lost without the prequel.

So now I am back, with a shorter point list to share my experiences:

• The motherboard I used was a Asus Strix B450-I.
  • I went with this board because it was the cheapest motherboard that:
    • Is mITX
    • Could swallow a 3900X
    • Has 2 M.2 slots.
• The cooler I used was the one I used last time: Alpenföhn Black Ridge, with the original fan removed and a Noctua NF-A12x15 put on top as intake (sucking fresh air in and blowing it through the fins onto the motherboard).
  • This is actually a ideal setup as this will help cooling the VRMs a little, even if it's hot air.
  • I know there is some scare about if the Alpenföhn works with some AM4 motherboards. I can report the Black Ridge, atleast the one I have, fits perfectly on the Strix B450-I without modification:
• Other specs are the same as my post from last summer, except I upgraded to 32 GB RAM:
  • Corsair SF600 Platinum
  • GTX 1080 TI FE
  • Corsair 2x16 GB LPX 3200MHz
  • Intel 660P 2 TB
• For short bursts of workload, i.e. gaming, the 3900X will do just fine on its own with the Black Ridge in the Ghost S1 case. You don't have to worry about it.
  • This is true in general about all CPUs and cooler combinations if you are just gaming.
  • You could get the tiny Noctua L9A cooler and use it with the 3900X if you are just gaming.
  • The thing is though, if you got the 3900X, you likely aren't just gaming. You probably run long workloads too.
• For long workloads, 15+ mins or so, the motherboard's VRMs and CPU gets toasty.
  • The CPU will hit 95 C and throttle, and the motherboards VRM's will get up there too.
  • The best and easiest way to fix this, is to add a exhaust fan (preferably a Noctua NF-A12x25) above the CPU/motherboard.
    • Inverting the case and adding a NF-A12x25 on the inside in the top as exhaust will keep the CPU from thermal throttling but VRM's still get toasty.
    • Adding a NF-A12x25 right above the motherboard will solve all your issues, and is the best you can do without going for liquid. I think only one fan will suffice, but since there's room for two in the tophat, I have two.
    • See the graphs below for results and pictures of the setups.
• Good video from Optimum Tech about cooling a 3950X with low profile coolers: Ryzen 3950X vs. Low Profile Coolers - Sanity Check
  • Unfortunately, he doesn't test the Alpenföhn, but he does test the Noctua L12S which is similar.
• The Asus boards seem to have a hardcoded limit where 75 C means 100% fan speed.
  • Unfortunately, this means even with custom fan curves and fan smoothing settings your fans will occasionally rev up for no reason. I recommend using a Noctua Low Noise Adapter for the CPU fan to help with this.
    • This does ofcourse mean everything will run a little hotter, but a little quieter also.
  • Liquid coolers have a big advantage when used with Ryzen as they won't annoyingly rev up and down, as their speed is based on liquid temperature.
• The Strix B450-I will make the PCI-express slot run at 8x if both M.2 slots are used.
  • Apparently this shouldn't really matter but it fundamentally bothers me so I only end up using one of the M.2's anyway.
• I have not looked into undervolting/underclocking. If you're not super keen on getting all the performance you could probably look into doing that.

Let's Look At Some Graphs

CPU and VRM Temps With The Different Configurations

Temps were logged using HWiNFO64, while transcoding the first hour of the Godfather Blu-Ray to x264.

Be mindful of the Y scale. I don't wanna make clickbait graphs, but they're easier to look at.

First, lets look at CPU temps:

• The standard configuration comes uncomfortably close to the 95 C thermal throttle
• Flipping the case and adding a NF-A12x25 on the inside as exhaust in the top helps a little, should prevent it from hitting 95 C
• Adding one or two NF-A12x25 on top, like in a tophat, is ridiculously effective, even if you case isn't inverted. No chance for the CPU to go over 90 C.

Perhaps more important in a configuration like this are the VRM's however:

• Standard configuration is very uncomfortably warm, and it'll probably keep on going up if the test was longer. Not recommended for prolonged use.
• Inverting the case and adding a top exhaust fan on the inside helps, or at least slows the heating down.
• Adding NF-A12x25's as if they were in a tophat, is super effective. Notice here that the Inverted LNA test performs better than Standard Max RPM.
• Two NF-A12x25's is of course silly loud, but good lord it's a tornado.

Fans Matter!

Something I tried early on was comparing the Noctua S12A fans to the A12x25 fans. I believe I had two of them mounted externally (pseudo tophat, because I didn't have one yet), running at max RPM.

It's quite a difference:

The A12x25's are incredible. It's like you have a tornado in your room.

Conclusion

3900X in a Ghost is possible on air, but you should really get a exhaust fan right above the motherboard, so you probably wanna get a tophat... but if you're getting a tophat anyway maybe you should look into getting a large tophat and going for liquid cooling instead.

I mean, you can do it on air, but I don't feel super comfortable leaving it on overnight to batch process video encodes. It's a little too warm for my taste.

More Pictures

I know looking at SFF builds can be appealing, so here, have some more random pictures of my build in its various states:

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Thanks for reading.