Optimal Airflow with ML RGB Fans

Hello there,

 

I'm currently using a NZXT H700 case with 3 exhaust fans (ML RGB Fans x1 on the back, x2 on top) and 4 ML (x2 RGB, x2 WLED) on my H115i radiator. Will there be any problem performance wise if I would add a 4th exhaust fan on the top of my chassis?

 

You see, H700 doesn't have the ideal top panel as it's not mesh so I would like to keep things cool inside my chassis, especially with the GPU running on 74-76 Celsius, maybe i would see a drop on gpu temp as well?

Try doing a custom fan curve for the GPU first, if you haven't already. More exhaust fans will likely get you into a negative pressure situation with little benefit.

 

Do you have any way to measure the internal case temperature?

Most likely no benefit and quite possibly it will be detrimental depending on where the 3rd top exhaust is located. When it comes to case temperature, you are regulating it by exhausting warm air and replacing it with other air (hopefully colder). However, you can't really take out more than you bring in and in this scenario the most likely result is the top exhaust panel will try to draw from somewhere else - probably the back mesh. That is not optimal and may bring some of the GPU waste heat that would normally float out the back on its own, into the main central area of the case. The only thing an extra top exhaust might help with is if you felt the CPU radiator exhaust was having a negative effect on the case or GPU. An extra top exhaust might help move it out a little faster, although I having trouble seeing a gain in 2x120 vs 3x120. Still there might be an aesthetic element to this and you can always balance your intake/exhaust in a more normal way... by regulating fan speed. 3x120 at slow to moderate may be preferable to 2x120 at moderate to high speed.

 

As mentioned above, only the GPU's own fans are going to make much headway with actual GPU temp reduction. If you start to notice you get a definite heat soak effect where 20-30min down the line temps really take a turn for the worse, then it may be environmental. In those cases, you need pretty direct disruption of the air around the card. Top exhaust won't do it. It would need to be a side fan (rare these days) or a very strong low intake, something probably not available in the current configuration.

Try doing a custom fan curve for the GPU first, if you haven't already. More exhaust fans will likely get you into a negative pressure situation with little benefit.

 

Do you have any way to measure the internal case temperature?

 

Not yet, at some point I'll just get an external thermal sensor as you suggested me a while back

@C-attack, thank you for the reply as well. I see your points and I conclude to the fact that a 3rd top exhaust fan won't be required.

 

I'll try to create a custom fan curved though I'm not annoyed by the 76C on the GPU. I just thought not enough air getting out of the case as the reason it happened. According to EVGA this is a normal temp for the iCX GTX 1080

One thing for sure is DO NOT use the "zero fan" mode that delays start up until 55/60C when you know you are going to be under load. For the desktop work that's fine, but letting the fans come on like a freight train at 60C will make it so you are always playing catch up with temps. Give yourself a reasonable quiet but on (30-40%) at the lower temps to delay the heat soak build up as long as you can.

 

Another way to look for environmental heat is with fixed load GPU tests or anything fairly steady. You will be able to see environmental heat as a slow +1C every 2-3 minutes on the GPU temp graph. Of course, you can measure it directly with the temp probes as suggested above. I am in the middle of this kind of thing right now trying to squeeze some new hardware into my case and with radiators in new positions. The C-Pro has my water in/out and two more ambient probes on the intake sides to help me figure it out.

So do you have any recommended graph on the GPU custom curve? Have no clue how to modify it, but yeah, i have it on Zero RPM as default.

Set the curve from within Afterburner or EVGA Precision, which ever of the two you prefer to use (does Asus Tweak still exist?). Both probably have a 30% minimum speed or so and that may also depend on the GPU model. You can set it as low as you like, as long as it's moving. There is definite difference between zero rpm and 30%. My old 970s in SLI would hit 55C at the desktop in zero mode. With 30% fan they were both in the upper 30s. In both programs you can save the fan profile to the GPU clock/mem profile. That makes it easy to have zero mode (Afterburner/Prec. X not running) or launch it and apply profile #1 - now the fans run. As for actual speeds, just set your preference. It is definitely noise and GPU model specific. There is no mathematical threshold you need to meet for airflow.

Alright thank you!