Fractal Design R6 improving airflow and thermals

Electric_Eclectic · October 16, 2018

Hello LTT folks -

I'm planning a build using the Fractal Design Define R6. The stock fan configuration seems "pretty good" but I was looking at options to improve air cooling since I may end up running an overclocked high-end processor and eventually 2080 or some other space heater inside the case. I don't think you can get 3x140 in the front especially with the 5.25 bay up top which I might actually use, so here's what I'm looking at:

Option 1: Open top vents, no additional fans.

Opening the top vents seems in some reviews to add some cooling performance with a minimal increased noise. I'm a little concerned that this will steal some air pressure focusing front airflow towards the CPU and out the back, but it does give me more space to exhaust air FROM and hot air rises (though fan airflow paths matter more I think) and the tests in the reviews I saw that did them did show better thermals with minimal additional noise.

Option 2: Open top vent, 1 or 2 additional fans exhausting there.

More noise from fans is a given, but here I'd be pulling air across the CPU heatsink negating some of my fear from option 1 (though this air is more likely to be warmer air from the GPU) and importantly providing some pull for hot air from the GPU up and away from the GPU which seems to be the primary area of airflow/heat concern with this case (hot air trapped between the PSU shroud and the GPU).

Option 3: A bottom intake fan.

This would help ensure positive air pressure and I can get enough clearance under/around the case for this, but this intake would be at a right angle 90 degrees with the front intakes. There are technically 2 spots for that, and there's a good, easily removable dust filter for them. I'm worried about cross flow messing with airflow making more noise or preventing air from moving back to the GPU intake if I use the frontmost slot - but there appears to be room to put one in the middle-bottom slot where this is less of a concern, maybe? This could pair nicely with option 1's top-vent, maybe get some bottom/front -> top/back airflow going to pull hot air away from the GPU? The bottom vents are visible here: https://youtu.be/LJNBcR46tYA?t=1277

Questions:

1. Should I be worried about right angle airflow creating more noise with option 3?

2. Should I be worried that somehow this will direct airflow up before it gets to the GPU, trapping more hot air between the GPU and PSU shroud?

3. Are these less of a problem if I use the middle-bottom slot as opposed to the front-bottom?

I'm not 100% sure how usable that bottom-middle fan slot is with PSU cabling but I hope it'd work. I could also try the bottom-front slot and doing some kind of custom shroud that would sit at a 45 degree angle right over the bottom intake fan, directing that air backwards through the PSU shroud in the hopes that it helps drive airflow through the vents in the shroud that are right underneath the GPU air intake. I feel like that would eliminate my concerns about cross airflow if I had to use that spot. Not sure how much air would realistically exit that way but if I have positive pressure and the fan driving air in there, it seems it might help.

My last thought is maybe this is all overkill and I should keep the solid top for acoustics, and just open the front-panel door whenever I'm gaming, since "removed front panel" seems to lead to so much better thermals... then shut it the rest of the day. Can't see the front-panel when I'm sitting at my desk gaming anyhow.

Below here are details about some of my build plans and priorities to hopefully stave off some common questions I can anticipate that could change responses:

I'm not really interested in other case suggestions unless you're SURE it meets or exceeds based on all of my priorities, so REALLY looking for feedback on case airflow options in that specific case. I've not BOUGHT this case already but my mind is close to made up on that so something would have to blow me away. Here are my priorities:

1. "Good enough" airflow WHILE maintaining very good acoustics.

2. Good build quality / features / flexibility.

3. Minimalist / clean design aesthetic - e.g. no RGB light pollution, prefer solid black, probably won't get the TG version even though I plan to take care for clean/pretty cable routing/etc.

There are a minimum of 4 and sometimes as many as 5-6 PCs in my office and I spend the day on the phone, so acoustics are a higher priority for me than most people. Within that constraint, I want as much airflow for overclocking options and performance for when I'm gaming. I am conflicted but leaning heavily to air cooling because the best air coolers have comparable thermals, cost less, with less risk that a pump gets noisy over time or worse - so I have no radiator placement concerns to work with. I kept my current PC for like 6+ years and I'll be building 2 of these so I feel like odds are the AIO option's increased maintenance risk is too big a factor - more things to go wrong, higher potential for an expensive or involved repair. I expect to use a multiple-fan non-blower-style GPU. My PSU will be pulling air from below isolated from the case.

Curufinwe_wins · October 16, 2018

As long as you get a good cooler in the end, you really don't need to worry about thermals in that case with or without the panel open.

I've done almost all those different variants with my own fractal cases (r5 and s), but it's more for min-maxing at the end.

Opening the door when you are really worried is a nice first step, but I would put the whole thing together and see if you see any reason for concern anyways. I don't really expect you to.

1 really isn't an issue, 2 isn't either. The ducting of airflow is less and less an issue the lower speed your air is moving. If you want to optimize for noise, you will probably be wanting to run fairly slow with the fans anyways.

Bottom intake is fine, if your psu length allows for it. Exhausting out the back/top will be better most likely just because it is less restricted.

Electric_Eclectic · October 16, 2018

Thanks for the time to reply, and the analysis. I think even as I wrote that I started leaning heavily to setting up the bottom-middle intake as an option. (Nothing like having to explain your thought process to others to help your own opinions crystallize!) I can always run it at minimum rpm or even unplug it if it doesn't seem worth the additional noise. Swapping out the top cover for more venting and opening the door are both things I can do easily after the system is built so I can do that more on an "as-needed" basis - the increased airflow seems substantial, so it might be worth it when I'm running OC for extended game sessions.

I kept watching reviews last night and it does look like there's probably enough room for a normal-sized PSU and still have some cable room between the PSU and the middle fan. I'll look at the dimensions more closely on the case and PSU.

FWIW, here's why i think some accommodation may be worth this extra effort:

See the Gamers Nexus review at the positioned link - shows a full 10c temperature difference between stock and "no front" (which I assume is more or less the same with "open door" though they didn't test that explicitly.) Suggests there's a pretty meaningful improvement to be made with better airflow.

An argument for the extra bottom intake - shortly after that CPU temp, that same review shows that GPU temp is not nearly as affected by removing the front panel, which means even more air through those front fans doesn't seem to significantly change the air feeding into the GPU intake - presumably this is getting pulled up to that back exhaust before it gets there, but there could be dead-spots and drive obstructions factoring in. Pulling some fresh air right to that GPU intake area seems like it'd help nudge GPU temps down. Since GPUs in general and Pascal GPUs in particular are reportedly pretty aggressive about throttling clocks as they heat up, this could have reasonable performance impacts.