Discussion Dan A4 SFX v4.1 + Asatek 645lt Intake or Exhaust Questions


Cable Smoosher
Original poster
Jun 21, 2020
Hey All,

First post here, good times : ) I'm an SFF enthusiast currently holding onto an S4M, Ghost S1 and newest Dan A4 SFX build. I'm hoping there are some experienced Dan A4 or 645lt users out there running with the NF-a9x14. I have to preface, I'm not super interested in users who are using a beefier fan or users running the fan affixed to the bottom of the case and the radiator on top of that since those configs are significantly different enough to possibly not apply to me.

Dan A4 v4.1
ASRock X570 Phantom ITX
Corsair SF750
AMD 3700x
Asatek 645lt AIO with a NF-A9X14 Chromax
pslatecustoms cables for all PSU cables
EVGA 2080 Ti XC Gaming

I opted to go against the grain and put the Noctua radiator fan in the push/exhaust config. I figured I would test this way and in the pull/intake config later. Unfortunately, I didn't account for how challenging the build is and now I'm not keen on taking the whole thing apart in order to try.

I'd like to think I've read just about every forum post and reddit thread on the question of 645lt intake vs exhaust, but I wanted to raise the question again for any experienced users to comment on.

My initial as to why I went with push/exhaust is a bit complex. Here are the PROs in my reasoning:
1) The ASRock X570 Phantom ITX chipset fan is loud and annoying. The bios does offer control over its speed which is great, but at critical temps it turns on no matter what. I want to keep the case internals as cool as possible to keep that thing off. Therefore, using intake with the 645lt is another factor adding to the heat inside the case.

On the ASRock, the M.2 slot is on the back of the MB with no heatsync. Again this is another reason to want to keep heat down inside the case.

2) As a video game dev in Unreal Engine, my GPU is almost always running at full blast and I don't want to get to throttle temps. Again, running the 645lt, I reason, could increase GPU temps.

3) no GPU throttling. Even with two monitors plugged in, when I run a stress test like OctaneBench I hit about 80c max.

Now here are the (maybe) cons I am experiencing:
1) when I cold boot, my 3700x idle temps are around 43-50c in ECO MODE. I think this is perfectly reasonable and I would be happy with this, but after the machine is running for about 20 minutes, idle temps rise and flatten out around 60c and with constant PBO boosting even when using Chrome for example the temp on average is probably closer to 65-70c. That may seem high, but I assume that this is due to the liquid temperature reaching its equilibrium. That's just how warm that temperature is gonna stay given how much heat it can exhaust over time.

Now, although my idle temps are close to 70c, if I now run Cinebench R20, you may be surprised to know my temps don't rise much. I'm still in the 70-75c range for the duration of the Cinebench R20 run. My score is around 4350 (remember i'm in ECO MODE).

I am bummed my idle temps are so high but i'm fine with that full load temp!

Should I take this machine apart and try pull/intake? Of the 100 or so posts on this issue I've read, I saw one or two people mentioned a 3-5c gain on CPU temps, but that there will be an impact on the GPU temps (i haven't seen any numbers for this though).

The fact that my idle temps rise 10c after 20-30 minutes of the comp being on is strange and I wonder if this would be the same in a pull/intake config anyways even if overall I gain 5c max (don't think that's worth it probs?).

I've also read some people complain that pull/intake led to their Corsair SF power supply fan turning on and overall increased fan noise. This does concern me. I do value silence and as of right now I can only hear the Noctua fan spin up on that annoying AMD boosting, otherwise the case is so silent i can only ever hear the pump.