2x140mm or 3x120mm in the front

I just bought an Obsidian 500D RGB SE that comes with 3x120mm LL RGB fans in the front.

 

I'm considering replacing them with ML fans since I understand these are superior to the LL fans but please correct me if that is not correct.

 

Next I'm thinking whether I should get 3x120mm or 2x140mm.

 

I'm guessing 3x120mm fans will move more air and thus provide more cooling inside the case vs 2x140mm but probably at the expense of more noise?

 

Many thanks in advance for your tips and input!

The ML are only going to be superior if you have a 360mm radiator strapped behind those fans. Even then, on a CPU cooler with wattage in the 180-200 range, your talking about 0.5-1.0C of coolant temp. The LL are visually impressive to be sure. Might be hard to go a ML after that, but you can synthesize it right now by turning off the outer ring and just using the 4 inner LEDs to light the way. (I see now you already have two on the platinum). If there is some drastic need for massive intake airflow, you may need more than RGB fans and look toward the definitely noisier 2000 rpm crowd.

 

In regard to the other part of your query, 120x3 will always beat 2x140 for airflow unless you cherry pick opposite extremes (blaster 140mm fans and lowest noise profile 120s). Also, depending on your intention the 120x3 usually has a more focused flow. Most 140s have a moderate to wide spray pattern. That means the average 120mm fan is better for direct cooling M.2 drives, disrupting air around a GPU, etc. I've been messing with this all week as a means to drive some bottom radiator intake heat out the back. Both work, but the 120mm is more focused for the task, even when adjusting both types of fan for noise (3x120@1000 is probably quieter than 2x140@900 trying to make the same volume of air as 3 fans). However, the final say often goes down to the case and mounting system. Nothing ruins the fun of a 140mm fan when you have a case flange sticking 25% into the intake path. Besides a reduction in airflow, it also adds high frequency noise. Most cases have clean, unobstructed 120mm mounting slots. Not all cases have unobstructed 140mm pathways.

 

You can see what the others say, but I would be hard pressed to give up 3x120LL for anything else without a really good reason or a total case makeover for another purpose.

Many thanks for your very detailed reply!

 

After what you say, I'll go with the 3x120mm LL fans that come with the 500D SE case and get a third one for the back of the case.

 

I'm all new to this RGB stuff coming from an old rig with zero RGB effects but figured it might be quite cool with these effects for my new rig. I also picked up 4x8 GB Corsair RGB DDR4 sticks so guess my case will look like a Christmas tree when I have everything up and running :D

 

Wasn't aware the RGB effect differ between the LL and ML fans. Will try to find some YouTube videos to compare. This also makes me wonder if I maybe should replace the ML fans that come with the H115i RGB Platinum with LL fans to match the existing 3 fans in the front and the extra LL 120mm fan I'll get for the back of the case.

 

Or maybe that would decrease the cooling performance of the H115i? I will use it to cool a delided 8086K where I have my hopes up it will end up running at 5+ GHz.

 

I'll mainly be using this new rig for X-Plane where the highest possible CPU speed is all that matters. Thus my choice of CPU rather than the new 9x00 series since speed matters more than number of cores.

The ML series have 4 inner mounted LEDs, so kind of a reverse of the standard LED with the 4 corner mounts. It looks nice, but compared to the 16 LEDs and ring of a LL, it's a hard sell. Would you give up anything by going LL on the H115i Plat? Probably not. There is no measurable difference with my 8700K@5.0/1.30v and about 180 peak watts. Usually less and thus coolant deltas are always the same. I gave this a good go with HD/ML/LL multiple times over this week. As you cross the 300W mark or potentially on thicker custom radiators, the differences become more apparent. This probably does not apply to your set up. I would give it a little time with what you have before deciding. You may prefer one or the other for any number of reasons. The included fans are sunk costs, so try them out an see.

I just watched a couple of videos to know what we're talking about here and now I fully understand what you mean when you say the LL fans look stunning...WOW!! The visual effect is miles ahead of the ML fans IMO.

 

After this I decided I will keep my LL fans in the front, get an LL fan for the back of the case as well as 2 extra 140mm LL fans to replace the ones that come with the H115i Platinum.

 

Like you suggest, I can't imagine the difference in temp will be that much.

 

Now I really need to get some sleep so I will feel fresh tomorrow when I'm about to put my new rig together :-)

 

Thanks again for all valuable help, much appreciated!