Question Should I change the CPU cooler or the case fans?

[builder2020]

Background:
I'm currently using a PC I built way back in 2009 with a few changes along the way.

CPU: AMD Phenom II X4 955 BE with stock cooler
Motherboard: Asus M4A79 Deluxe
Case: Nzxt Guardian 921 (2x 120mm intakes and 1x120mm exhaust)
Thermal Paste: Arctic Cooling MX-2
GPU: Sapphire RX560
Storage: 1HDD and 1SSD

No OC. Cool n Quiet enabled. A month ago the CPU fan started getting really noisy. So I checked the CPU temp with HWiNFO. It was idling at 61deg. Apparently, that is the cutoff temp for this CPU. So I replaced the thermal paste. This dropped the idle temp to less than 50deg. Surprisingly the 11 year old tube of paste still works fine.

Some crude testing:
Used CPU-Z for stressing the CPU and HWiINFO for monitoring temps and RPM. Ambient temp ~28deg. I tried using different combinations of the Asus Q-Fan option from the BIOS. Here are the results. I didn't take screenshots of the readings. Just noted them down.
(Sorry I couldn't figure out how to make a compact table.)

CPU Q Fan Mode​	CPU Fan RPM​	Case Q Fan Mode​	Case Fan 1 RPM​	Case Fan 2 RPM​	CPU Temp​	Noise​
Under Load​
Off	6550	Off	1300	1100	54.5	Vacuum cleaner
Performance	5000	Performance	1000	900	57.5	Extremely noisy
Optimal	4650	Optimal	950	850	59.5	Very noisy
Silent	4560	Silent	800	700	61	Noisy
Silent	4300	Performance	950	975	60	Bearable
Silent	4250	Off	1075	1225	59	Bearable
Idle​
Off	6250	Off	1300	1200	44.5	Vacuum cleaner
Performance	4400	Performance	990	840	46.5	Noisy
Optimal	4000	Optimal	880	770	47.5	Bearable
Silent	3950	Silent	770	620	48	Ok

So, I'm currently using the Silent/Off Q-Fan combination, which seems to be the best trade-off between temp and noise. I tried using speedfan to see if I could increase the case fan RPMs and drop the CPU RPM, but there was no manual control even after disabling Q-Fan from the BIOS. And neither does HWiNFO show the fan control icon. So I guess I'm out of luck with this motherboard. I want to squeeze as much out of this PC as possible. The PC will likely be used soon at ~40deg ambient. The 12deg increase in ambient will probably give an almost direct increase in the CPU temp and get it throttled.

Question:

Would it be worth it replace the cooler with say, a Noctua NH-U9S for better direct cooling for the CPU? (Cooler has to be <=150mm in this case or it's going to touch the fan on the side panel.)
Or should I replace the case fans with say, 3 x Noctua NF-S12B 1200 3-pin for more cold air into the case ?
I don't want to take both and spend double the cash. So, which option would be better in keeping everything cool and quiet?

 

[alceryes]

If your case fans are working, replacing them won't do that much whereas an upgrade from the stock CPU cooler would definitely help.
Replace the CPU cooler.

 

[builder2020]

Yes, I think the case fans are working fine. Although, I don't remember what RPM they used to be. Maybe I could take them out once and add a little engine oil to the bearings, just in case. That should get them back to shape, while I change the cooler.

Thank you! I'll post the updates once I'm done with the exercise.

 

[SkyNetRising]

I'm currently using a PC I built way back in 2009 with a few changes along the way.

Sure, you can get a better cpu cooler. That would help with temperatures slightly.
But ...

Ultimately you should be thinking about replacing core part of your system - cpu, motherboard, ram.
CPU is outdated and a power hog. It wasn't very good even, when it was released in 2009.

PC case is really bad in terms of air flow. Obstructed intake. I'd replace case too.

 

[builder2020]

Sure, you can get a better cpu cooler. That would help with temperatures slightly.
But ...

Ultimately you should be thinking about replacing core part of your system - cpu, motherboard, ram.
CPU is outdated and a power hog. It wasn't very good even, when it was released in 2009.

PC case is really bad in terms of air flow. Obstructed intake, small fans. I'd replace case too.

Yes, I will be getting a new build soon. Will be giving this PC off to the kids for as long as it goes. It's served me well for this long. Let's see how much longer it can go.

 

[builder2020]

I re-lubed the case fans with engine oil. Vibrations disappeared totally. Noise levels are noticeably lower. Did the same testing again. Ambient temp ~28deg. After the last time, figured the case fans were better off with Q-Fan turned off. So I changed only the CPU Q-Fan. Here are the results.

��

CPU Q Fan Mode	CPU Fan RPM	Case Q Fan Mode	Case Fan 1 RPM	Case Fan 2 RPM	CPU Temp	Noise
Under Load
Off	6250	Off	1240	1310	53.5	Vacuum Cleaner
Performance	4750	Off	1240	1310	56	Very Noisy
Optimal	4350	Off	1240	1310	57.5	Bearable
Silent	4050	Off	1240	1310	58.5	Ok
Idle
Off	5750	Off	1240	1310	42	Vacuum Cleaner
Performance	4125	Off	1240	1310	44	Bearable
Optimal	3575	Off	1240	1310	45	Ok
Silent	3560	Off	1240	1310	45	Ok

Just a reminder... The three case fans are DC running at 12V. Out of these the side panel fan doesn't have an RPM reading, just the front and rear ones. And only the CPU fan is PWM.

With Q-Fan Off for the case fans, their RPMs are constant throughout. I probably swapped the front and rear case fans. That would explain why the RPM dropped for one and rose for the other. In which case, both fans got a slight RPM boost after re-lube. The idle temps seem to have dropped 2.5 deg and the load temps around 0.5-1 deg. Could be because of any/all of the following: (1) slightly better airflow with the reduced wobble/vibrations (2) minor rpm boost (3) clean fans (not much build-up to begin with though). CPU Fan RPM dropped around 200-300 with a corresponding drop in noise levels.

Overall, more than the temps, the noise levels are much better after re-lube. Already ordered the Noctua NH-U9S. Hoping to get it in a few days. Will post the improvement after setting it up.

 

[builder2020]

Got the Noctua NH-U9S. Installed it and repeated the tests. Couldn't hear a thing, even with Q Fan turned off. The temps dropped 2deg in idle and 4.5deg under load. Not much change there with the temperatures. But man was it quiet!! The stock cooler had to scream it's lungs out to get anywhere near the noctua! And I had no idea what I was putting up with all these years!
��

CPU Q Fan Mode	CPU Fan RPM	Case Q Fan Mode	Case Fan 1 RPM	Case Fan 2 RPM	CPU Temp	Noise
Under Load
Off	2033	Off	1270	1350	49	Quiet
Performance	1215	Off	1270	1350	53.5	Quiet
Idle
Off	2033	Off	1270	1350	40	Quiet
Performance	1115	Off	1270	1350	42	Quiet

Thank you guys for your suggestions and sticking around. Can someone tell me how to mark this thread as closed?