I have an a1620n HP desktop and I had to recently get a new PSU. Ever since then the cpu fan is running very loud at its max speed (around 4000rpm). It is quiet when the computer boots for a few moments but it then jumps up to a high speed. It is noisy, does anyone have a suggestion on how to fix it?

There are two types of PSU (silent an ordinary) so original PSU is silent.

Heat is always a problem on PC of any kinds not serviced
ever clean it? of all that lint?
no OS stated,l 32bit OS will only do about 3.5GB, max.
on most cheaper PC that the GPU chip steals main ram to run.
all CPU made lower speed hot, inside the CPU CHIP
that is Intel magic inside doing that. deep where you cant go.
only cure is a good clean heatsink, good thermal bond compound
and good fan and a cas fan that runs. and works
the PSU has fan if it dies, how can the PSU keep cool
and the main chassis breath, unless it too has fan.
mine as I type has 4 fans
CPU
GPU
PSU
case.
all work and the case inside never ever overheats.
ever run a program to see CPU heat, ? it tell you its temperature.
do so and you see, omg it is too hot its like 90C.
this is the magic temp that the Intel inside kicks it and keeps CPU from burning itself up (they all do that since first Pentiums made to now)

that motherboard many not allow 4GB.
id have to look up the number stamped on it to be sure
this PC is old most are now scrapped. this old.
id scrape it and get a 64bit 2007 or newer PC with windows 7
there, or newer. I would, so it has value and a future.
HP has zero support on things this old. zip

again no OS stATED, BY you, how in the world can we guess that? and matters.
the old data sheet said 3GB max

https://www.cnet.com/products/hp-pavilion-a1050y/specs/

snopping about it says , Asus made it for HP under contract.
ASUS PTGD-LA
deep scans inside Hp finds this gem
4GB max, (and says less)
the fact is fining memory in 2016 for 12 year old mobo
and making its BIOS happy and that old Pentium 4.
is no fun at all, hard, and expensive.
Id up grade the PC before dumping cash on the wrothless
Pentiums are in the crush and recycle bin at Goodwill stores..




https://support.hp.com/us-en/document/c00361570

Check for proper connection, also check bios speed on fans and make sure heat sink is correctly installed... side note you have fresh item's and higher power faster speed... if there is a controller on fans lower them.

Did you get the same or higher wattage power supply? On the HP's the CPU fan runs (faster) when it gets hot. Assuming you don't have dust, are all the fans plugged in? It could be the new PS runs hotter, so you might need to add another chassis fan to offset. Also, I would get a CPU temperature applet just to see where it's at. HP might have some utilities built in that do this. I had a fan that was going bad, though it wasn't making noise, so the only way I knew was by checking temps.

Your computer is getting very hot it sounds like you may need a fan running near.

Check the CPU fan, it may be faulty and causes the CPU to overheat and shut down.

I would not recommend this. You could fry your cpu and then you would have no notebook. If you are going to open the notebook make sure there is nothing interfering with the fan. The fan can be replace. Take the fan out and try to replace it, if needed. Do not run the notebook without a fan.

Change fans. Fans do not have a long life.

cheek the cable of cable properly plug in
R
OFF YOUR pc and system cell put out for 10 mint put back in to the system and stat your system
R
cheek out fan for electric shot

repaly me if i solve your problem

My first check would be to see if the manufactuer has a BIOS update for the ma inboard that resolves that problem.

If they don't have one available on their website I would contact their technical support because it may be a known issue that they are currently working to correct.

At least knowing you'll know that a fix is only a few months away.

If the manufacturer claims that your problem can't be verified you may have a faulty thermal control unit on the mainboard.


Let me know what you find out.