changing fan in PSU

P

pdp76

Weaksauce
Joined
Jan 31, 2006
Messages
113
I recently got a In Win BK623 SFF case which comes with a nice little mATX power supply. The problem with it though is that the PSU fan is insanely loud at full speed, but it does move a lot of air to cool it and the case since it acts as the exhaust. But in the interest in quietting it down, since it is an HTPC, I replaced the PSU fan with a quieter one, though it only moves about half the CFM of air. This will probably cause the PSU to run hotter. What kind of signs should I look for if the PSU is getting too hot? So far, after idling for several hours, it only feels warm to the touch, but of course idling doesn't really stress it much. Thanks.
 
You should have asked this question before you replaced the fan and voided any warranty on it...

PSU's generally have thermal sensors that keep the PSU below a certain level. If the fan was running full speed the entire time, you should have RMA'd it due to a faulty fan control system. If the PSU overheats, they generally have overtemperature protections that would shut it down. However, there is a risk where as internal temps rises, ripple and voltage regulation may go out of spec, potentially damaging your equipment.
 
Tsumi said:
You should have asked this question before you replaced the fan and voided any warranty on it...

PSU's generally have thermal sensors that keep the PSU below a certain level. If the fan was running full speed the entire time, you should have RMA'd it due to a faulty fan control system. If the PSU overheats, they generally have overtemperature protections that would shut it down. However, there is a risk where as internal temps rises, ripple and voltage regulation may go out of spec, potentially damaging your equipment.
Click to expand...

There is no way I was going to keep using that PSU in my HTPC as it stood so I figured if I change out the fan and something bad happens to it, it's no big deal to me, I'll just get another quieter one later. And the PSU fan wasn't defective at all, it does start off slow and quiet, but after the computer warms up to idle temps the PSU fan is already at or very near full speed and it's way too loud.

Remember, the PSU fan is the only exhaust fan in the In Win BK623 mATX case. I have since added another PCI slot exhaust fan hoping it might help draw some heat away from the PSU, but not sure how effective it is. I'm also thinking about adding a small intake fan in the front of the case to see how it helps, but it will have to be a slow quiet fan as well.

Anyway, what you say about the ripple and voltage regulation could be a bit concerning, I will keep an eye on the voltages in the coming days, thanks!
 
You can't monitor the voltage unless you have three DMM's plugged in at all times. And there's no way you can check ripple without some very expensive equipment. Ripple is the bigger danger of the two.
 
If the fan speed is temperature controlled, shouldn't the controller automatically run the new, lower CFM fan fast enough, provided the power consumption remains well below the PSU's maximum rating?
But if the fan runs at full speed all the time, you should still be OK if you're running well below the PSU's maximum power rating.

I don't know if ripple increases with temperature, but power capacity drops, I think because of the transformer core material, and many years ago, PC Power & Cooling compared one of their 600W units to an unidentified 550W Enermax. They said their PSU lost 15% power capacity when the surrounding air went from 25C to 40C, while the Enermax lost 33%.
 
The fan controller will not work properly with any fan that does not have similar specs to the original one, since it is designed specifically for that fan. However, if the PSU isn't getting too hot, it should be alright, providing you aren't putting too much load on it (which is unlikely, since this is an HTPC). Of course, InWin PSUs are not the best quality to begin with, but they should be adequate for modest systems.
 
Zero82z said:
The fan controller will not work properly with any fan that does not have similar specs to the original one, since it is designed specifically for that fan. However, if the PSU isn't getting too hot, it should be alright, providing you aren't putting too much load on it (which is unlikely, since this is an HTPC). Of course, InWin PSUs are not the best quality to begin with, but they should be adequate for modest systems.
Click to expand...
This brings up another question I have, what exactly is "Too Hot"? When I said earlier the PSU is warm to the touch, it's just of the outer chassis of the PSU, it's kind of hard to get inside it while it's running to see exactly how hot it is.

As for the InWin PSU, it's not quite as crappy as I expected it to be. It actually has dual 12+V rails and it's also decently heavy for a small PSU (i.e. not the cheapest parts). The load I'm putting on it definitely isn't that big, I have an OCed E3300, but even at 3.33GHz, it should be just sipping electricity. The next big thing in it is an ATI AIWHD, basically a ATI HD3650 with a built in QAM tuner. That thing gets HOT... idles at around 70C so that should say something about the power it draws. I should get myself a Kill-A-Watt to see how hard the PSU is working.
 
You could put a pwm fan in it linked to the cpu fan header so it ramps up and down with the cpu.
 
rive22 said:
You could put a pwm fan in it linked to the cpu fan header so it ramps up and down with the cpu.
Click to expand...

Holy shit, that's brilliant!! Why the hell didn't I think of that? :D The fan I'm using doesn't have PWM, and my mobo doesn't adjust the fan speed via voltage so it will be running full speed the whole time, which is exactly what I want! The PSU controls the fan speed via voltage, which is not what I want. Only problem with that is the PSU is on the EXACT OPPOSITE side of the case as the mobo fan header... I'll just have to get an extension or something.
 
So far I've seen a stupid actions further encouraged by a stupid suggestions. The fan is running that loud for a reason, and that is to keep the PSU within its normal operating temps. Interfering with that interferes with that process.

In the age of modern PSU's, weight means little (especially with newer highly efficient power supplies requiring smaller heatsinks), and rails mean nearly absolutely nothing in terms of quality.

There is no way to tell how hot is too hot unless you have an oscilloscope measuring ripple. Good quality ones are good up to or above 50 C. Bad ones go out of spec in as little as 30-35 C.
 
He replaced a factory fan that was loud regardless of the RPM it was running at because it was a cheap fan. He put a new fan in there that is a bit quieter but still loud because he cannot control the RPM like many PSU's do for you. In that respect short of purchasing a new PSU all together, the idea I suggested is in fact a good one, as 'in general' the times when the PSU will need more airflow is when it is under load.
 
rive22 said:
He replaced a factory fan that was loud regardless of the RPM it was running at because it was a cheap fan. He put a new fan in there that is a bit quieter but still loud because he cannot control the RPM like many PSU's do for you. In that respect short of purchasing a new PSU all together, the idea I suggested is in fact a good one, as 'in general' the times when the PSU will need more airflow is when it is under load.
Click to expand...

He replaced a high RPM fan with a lower RPM fan to reduce its maximum noise level. He specifically stated the replaced fan has half the airflow of the original. Abd nowhere did he say he replaced with a better fan.

In 'general' does not work for 'specific' cases, especially since his only exhaust is the PSU fan.

And I have already detailed my reasons as to why it is not a good idea. If OP wants to risk frying his components, that's his problem; I already warned him of the risks and potential consequences of his actions.
 
The fans that come with those "less than steller" power supplies usually run at a maximum required rate to handle full load. Most of the time the PSU will not be under heavy load, putting a PWM fan in place remedies the situation. It is no different than your PSU in your system which has a variable speed fan on it. It's common freakin sense, you don't need a fan blowing at maximum rate when the unit isn't being taxed, and when it is being taxed the fan will ramp up.
 
Last edited:
Dude, I think this thread has regressed and digressed significantly. So let me just make this the final post as I think I have enough information.

Yes, I replaced the original PSU fan with a quieter fan that moves less air and yes, I do know the risks of it. All I wanted to know if there was any obvious way to gauge the risk or as I later realized a better way to put it, how can I know if it's too hot? Neither of these questions were really answered, which is all good because if I really need 1000's of dollars worth of equipment (oscilloscope, 3x DMM!) to get my questions answered, I will gladly take a risk, especially since my main goal is for a quieter HTPC and it doesn't seem like a huge risk. My guess/hope is that the PSU will fail or shut down before it affects any of my components.

But also note, I have tried to compensate by adding another PCI slot exhaust fan as well as considering getting another intake fan. Not sure if either one of these will mitigate the PSU heat directly, but I figure it can't hurt as long as I position the fans correctly and it will no doubt at least cool down the rest of the system.

The only helpful thing I got out of this thread was the suggestion to plug the new PSU fan into the motherboard instead of using the PSU to power it directly. This will at least help a little bit by guaranteeing the new PSU fan to run at 100% all the time (my mobo doesn't control fan speed other than the CPU fan) instead of having its speed voltage controlled by the PSU directly. Why do I think it will help? Because the new PSU fan moves less air overall so it would make sense to have it run constantly at full speed.
 
ok... after reading the general posts in this thread. i'll try my best to answer your questions.

the best solution at this point is to run the fan at 100% if you can bear with the sound. but honestly, wasting money on buying new fans and such isn't going to solve this solution.

better yet, invest that money on a new psu (i can recommend the cheapest but quality built) depending on your rig as well as budget.

i tell you this because the psu is one of the most important parts in a pc. usually when a psu goes out, it takes parts with it. last thing you need is a ghetto mod costing you more money in the long run.

good luck!
 
You must log in or register to reply here.
Back
Top