Yeah, exactly point on my fan model. Unfortunately i can only install 1 more extra fan which is below the front intake fan but I don't think it'll improve the air flow anyway since below there are where the extra cable resides.
I know that card is overkill but people from reddir (I asked) recommend to get it anyway for future proofing instead of getting 1660ti. Does this mean I have to forge another budget for better case?

Upgrading those fans would really hurt my budget right now for 4 of them. Case is no different here and that means I'd to save up more that what I had in mind initially. I've seen that ATX has better airflow mostly so is it better to just upgrade current case to ATX?

Oh, i need to add more fan too for ATX :sad:
Not when I asked about the product before. They said galax is a good card for both performance and cooling. If it run undee 80c, I would not worry at all but here I am, when the case itself was the problem

My 1060 run at 80c before upgraded but I didn't pay much attention to it because its fan wasn't as loud as this galax card

In the end, I opted for new case now. I bought Thermaltake Versa H27 TG ATX Case (same brand but eh, I like its build for the price), reuse all the case fans from previous case with 3 front intake, 1 rear exhaust and 1 top exhaust.

Tested case under idle
CPU: 40c (3.2GHz)
GPU: 42c (400MHz)
GPU Fan speed: 50%

Tested on load (MHW Very high preset)
CPU: 65c (3.7GHz)
GPU: 80c (1825MHz)
GPU Fan Speed: 80%

Test on load (Supersition Benchmark Extreme Preset)
CPU: 46c
GPU: 79c (1825MHz)
GPU Fan Speed: 79%

It seems by opting for new ATX case, I was able to shave off 3c on load but at least this time, it can run on boost clock without it downclock itself on thermal limit. I hope this would be enough until I bought better case fans later on down the road

P/s: thanks everyone for helping and provide suggestion for my problem. Really appreciate it.

The seller I go when I bought those case do recommend me to get the TT pure fan pack for like rm239 and he said it's a good fan to opt for but I still hold on from buying it yet. Need more advice for better case fans. Also can't find noctua fans at lowyat, probably need to survey more shops later.

All those front intake fan and top exhaust fan were wired to a 3-pin splitter to molex so can't really control much but low and high switch which I assume is 5v/12v switch

Huh, that's new for me, I didn't knew there was industrial ppc until you guys brought it up, definitely will look for it to assist with my air cooling setup build. Another thing that I learnt from the link you gave me, putting sleeve bearing fan (which is all of my current case fans) other than vertical position would have higher failure rate.

For PWM, I do need to get at least a controller right? My new case do not have built-in PWM support
My new case can support up to 7 120mm fans or 4 120mm x 2 140mm fans as the front panel can only support 120mm fan. I find this as no issue, as long there's 3 slot. I'm planning to replace those front panel fans as your suggestion with 2 or 3 industrial ppc fans while moving the current one to top intake. It would wear out the current fan but it's cheap to replace anyway. Later in the road, swapping those top intake fan to better fan or aio. Only concern with this setup is the type of airflow in the case.

Does the corsair LL 120 really good? I'm having doubt looking at the fan spec, about 40 CFM each which is like my sickleflow fan(?) Lets just say I'm ignoring all the fancy rgb and prefer performance.