XPS 8950, warranty replaced PSU, fans rattling returned

Sure they replaced the PSU fans?  I'd think they'd be more likely just to put in a whole new PSU.

Users shouldn't attempt to replace fans inside a PSU which can potentially expose them to high voltages...

See if there's anything informative in this thread...

@RoHe​

This is what was returned to me. I note that it is singular. Since I posted earlier today, I disconnected Fan #1--which is the one that appeared to be making the racket (it's the upper one with the PSU in place). Guess what, no more rattling noise. Since there are two fans in the unit. I'm pretty sure running only one isn't going to be acceptable for the duration. I thought I would receive another whole unit, also. It seems reasonable to assume it's the fan itself and not the connection to its control board. I'm not an electronics guru. I can deal with the mechanical aspects and, often, the software issues, but not how the electronics work. I think the fans are probably generic (as opposed the the PSU itself) and I can probably buy 50 for what a new or even used replacement PSU would cost. I don't doubt your "high voltage" warning although I'm not sure exactly what could be damaged: the control board? the fan? the entire pc once the unit is re-installed? the user? Obviously an electrical issue rather an electronics one. 

I continued to search for the thread that spoke to the "best" XPS 8950 750w PSU model. Although I haven't located it, I did read another who claimed (based on his experiences), that the acbel mp23y as well as the LiteOn 5tvr6, had very loud fans; the Chicony m92dc was the most noiseless. Although, since I disconnected the fan, the acbel seems to be absolutely mute.

I appreciate that you responded. The link goes to the thread from which I copied the certified PSU's; I'm familiar with it.

EDIT: After finally getting in touch with Dell, the chat agent said that the entire PSU had been replaced. I have an extended warranty through AmEx; however, I have to send in my PC to get a repair estimate. After the 4 mos I had to wait last year, that's not an option I'm willing to accept. I know that the PSU is around $200. If I knew for certain that it was a Chicony model, I'd order it--even taking a chance with that one. (I haven't found a Chicony model on fleabay, either--lots of ACBEL--the one I have.) I might be able to find out through sales. The chat agent assured me that I received the correct PSU for my PC--which I did. In any case, I wanted to report back. I received a lot of positive support on this forum.

You're apparently talking about the XPS 8950 chassis fan (#21), not the PSU fan... That's an entirely different story and you shouldn't need to replace the PSU or the PSU fan.

I'd go back to Dell Tech Support and explain that their replacement chassis fan failed, and ask if they can provide another one (free) from a different manufacturer for a DIY fan replacement. Know the Dell Part Number and/or manufacturer of the fan you have now, so you can try to get one from a different manufacturer.

If they don't agree, there are some aftermarket chassis fans that work with the XPS 8950, but  others cause a "fan failure" error when you boot because BIOS doesn't see/recognize the aftermarket fan. You'd have to press F1 to continue the boot if you get that error, but BIOS won't be able to adjust that new fan's speed. That means you have to be selective in which replacement fan to buy. Read this thread for some info on this topic.

And you can always contact Dell Spare Parts (1-800-357-3355) to get price/availability of their OEM chassis fan for XPS 8950 for a DIY. Have Service Tag available when you contact Spare Parts. (Don't post Service Tag here.) Again, know the Dell Part Number and/or manufacturer of the fan you have now before you call, so you can try to order one from a different manufacturer...

BTW: Similar chassis fan noise issues in XPS 8950 reported in this thread.

Read the last post by user thisdoesntwork who may have found a solution, but never came back to say if the noise returned after a while or not...

@RoHe​  My pc has 2 chassis fans, the one you reference is labeled FAN 1 and is on the back of the case; the other is FAN 2 which is on the front of the case. I understand that you believe it's the/a chassis fan. It is not. I don't know if Dell replaced a chassis fan or a PSU fan. (Which, I agree, should not need to be replaced--unless it's defective. I had read posts on this forum where the clients had an extremely difficult time trying to convince online tech support that they needed PSU fan repair rather than chassis fan repair.) On its return, I was very frustrated that I had received no further info regarding the repair. I do not know if they had to wait nearly 4 mos for the chassis fans to restock. I do know that for about 8 mos, my pc ran quietly--just as it had its first 8 mos. 

This is the one. After I disconnected it from its control board (I don't know what else to call it), the noise stopped. Incidentally, these fans do seem to run constantly. (I've had the case cover off for several weeks while trying to make certain of the noise location). I mention that because while researching, I ran across many posts that say that psu fans never run constantly.  I tried to run a SupportAssist hardware scan on it, but there is no PSU listing on the hardware list in the scan options. I reattached the fan as that dis-connect appeared to have slowed my pc to a crawl. That was about 30 min ago. The rattling has not become constant, yet, but it's there. Except for asking for a chassis fan, I will follow up with tech support. 

Again, I appreciate your efforts.

I see the chassis fan and the heat sink fan in the exploded image of the inside of the XPS 8950.  So are you really talking about the CPU fan (#20)?  That could explain why the PC slows to a crawl when the fan is disconnected because the CPU is overheating and throttling down to prevent it from getting fried.

Either way, Tech Support should probably have a record of exactly which fan they replaced previously, so talk to them...

@ritchea​ , review the thread below.  Follow instruction from Chris M and create a video while the noise is happening.  Working with Dell Cares agent and maybe Dell can replace another different PSU for you.

https://www.dell.com/community/en/conversations/xps-desktops/xps-8950-psu-unreasonable-fan-noise/647f995cf4ccf8a8decac868?keyword=xps%208950%20psu%20rattle

@RoHe​ For further clarification

"Tech Support should probably have a record of exactly which fan they replaced previously, so talk to them" Thank you for this. It helps to know what I need to request.

@Chino de Oro​ Thank you. I have the video and just haven't taken the time/mentally prepared to deal with support. 

@ritchea - Sorry, and no offense intended, but are you sure this is an XPS 8950?  I can't make heads/tails of the motherboard pic in your post vs the one in the XPS 8950 Service Manual.

In your image there's a horizontal white connector to the left of the fan connector you marked, and there are 5 blue/white capacitors directly above it. 

In the Service Manual, I only see one similar horizontal white connector on the motherboard (#13), but without 5 capacitors above it.  Even when I flip Dell's pic to put the white connector in same relative position as in your pic: the white connector is on the opposite side from where the fan connectors are marked (#20 and #21) in the Service Manual:

I guess it's possible the Service Manual has the wrong image...

Either way if you can see the fan, it's not likely to be the PSU fan. The PSU fan should be entirely inside the PSU's closed metal box.

@RoHe​ , the picture was the inside of a power supply.

@RoHe​ No offense taken. You have been quite helpful. As Chino de Oro (thank you) pointed out, that's the inside of the power supply. That's where the noise is except when I detached FAN1 from it's control board.

I tried to locate the PS model looking at my 8950 but just not seeing it.

Whichever one I have has been great since early 2022.

Maybe my original Dell order would show it.

I checked the specs but no clear indication of the part # or it's just not one of those you listed.

@Element115s4​ Thanks. Mine was purchased in early 2022. The model for my PSU is on the label which shows without removing it from the pc case. I don't know about yours. I'm happy for you that you have no issues. I assume most do not. Currently, mine has turned to nearly silent again. That's how I know the rattling is not supposed to be there. I even processed video (the most intensive thing I do on it) on Friday for a few hours, and it was relatively quiet.  Unfortunately, my history with this device says it will start rattling again. 

@ritchea​ 

Yes, that label must be under some extra plating and plastic that holds the RTX securely in place.

I can say looking at your pic that my PS is 1-2" shorter than yours.

Mine doesn't even reach or extend past that Dell logo above it on the board.

Well, we do know they are different so if others in here can weigh in, maybe we can get a consensus of which ones do vs don't have problems. :)

I realize there can still be lemons.