Temperature difference between 3x 140mm exhausts and 2x 140mm exhausts + 1x 120mm exhaust?

[ProtoflareX]

Let's assume for a second, that two different PC rigs have the same case, same GPU and same CPU air cooler. However, rig #1 has two 140mm top exhaust fans and one 140mm rear exhaust fan, whereas rig #2 has the same two 140mm top exhaust fans, but one 120mm rear exhaust fan instead of a 140mm fan. I would like to know how much CPU and GPU temperatures in rig #2 would suffer due to the replacement of the 140mm rear exhaust fan with a 120mm fan.

[SpaceGhostC2C]

Approximately 0°C.

[ProtoflareX]

6 minutes ago, SpaceGhostC2C said:

Approximately 0°C.

I was hoping this would be the answer, as it will save me some money, but it seems a little too good to be true, haha. Surely there would be at least a 2°C increase in temps?

[SpaceGhostC2C]

Just now, ProtoflareX said:

I was hoping this would be the answer, as it will save me some money, but it seems a little too good to be true, haha. Surely there would be at least a 2°C increase in temps?

No, very unlikely. Differences in size can matter as much as differences between models of the same size. You'll typically have higher static pressure and lower airflow with 120mm compared to 140mm, other things equal, but any (or both) of these statements can be reversed by choosing different fan blade designs, or even just running the fans at different speeds.

Heck, sometimes even the difference between having a fan and having no fan is negligible, and adding more fans isn't always the best course of action (as you can induce some weird airflows and air pockets inside the case).

[ProtoflareX]

20 minutes ago, SpaceGhostC2C said:

No, very unlikely. Differences in size can matter as much as differences between models of the same size. You'll typically have higher static pressure and lower airflow with 120mm compared to 140mm, other things equal, but any (or both) of these statements can be reversed by choosing different fan blade designs, or even just running the fans at different speeds.

Heck, sometimes even the difference between having a fan and having no fan is negligible, and adding more fans isn't always the best course of action (as you can induce some weird airflows and air pockets inside the case).

Interesting, maybe I was overstating the differences between 140mm fans and 120mm fans. Thanks for taking the time to answer my question.