it is better to have an exhaust fan rather than one intake alone... intake alone if it's true will push fresh air inside the case, you will have no circulation or flow of the air inside the case at all, warm and hot air will win over fresh and all temps will be over the place.. having a single fan as exhaust even if there's no intake will cause negative airflow which will work better for overall pc cooling.
Personally I disagree.
The biggest issue with negative air pressure inside the case (more exhaust than intake) is dust. When you maintain negative pressure inside the case, that means your case will be sucking in air (and dust) from every hole on every side of the case. Also consider that power-supply fans almost exclusively exhaust hot air out of the case. With only an exhaust case fan, it's going to be fighting against your power-supply fan.
If you go with positive air pressure inside the case (more intake than exhaust), you have 100% control over exactly where air will enter your case. The random holes in the case will be exhausting air, not sucking it in. That makes it easy and practical to install dust filters, so dust never even enters your case. It's a lot easier to clean a dust filter than it is to haul your entire case outside and blow it out. Your case airflow also won't be fighting against your power-supply fan, you will be helping it.
No, if your using typical tower case and intake fans have decent pressure rating (1.5mmH2O @ approx 1400rpm) exhaust fan is rarely needed. I build several computers every month and rarely use exhaust fans. Most are tower case with 2x-3x 140mm or 2x-4x 120mm front intake fans and sometimes a bottom intake as well. Link below has more details about this kind of setup.Might be an off topic, if I have only an intake fan and not an outtake, is it going to be worth? I read that while it can lower the temp, not having an outtake fan will blow a lot of dust in.
My bad. You are correct, I misunderstood what you posted.I think you misunderstood what I said. I was talking about the direction of the airflow, not the location of the fan within the PSU. The fan may be sucking in air (from the inside of the case) into the PSU, but it's exhausting the air outside of the case through the exterior vent holes in the rear of the PSU. I believe from reading the rest of your post that we are actually in agreement.
I agree that we are not talking about high amounts of pressure, but I clean out enough old dells each week to see that even with one single exhaust fan, that small amount of negative pressure is enough to cause dust and pet hair to collect at every possible intake location around the case.