# CPU fan short, Power Supply or Mobo issue?



## grinkyfizz (Jan 13, 2011)

Ok, unfortunately I don't have the full specs on me right now, but I'm helping a friend fix his computer.

It's a pre-built Gateway gaming machine, roughly 2 years old, Intel core 2 quad (not sure of the clock speed), 4 gig ram, GeForce video card.

According to him, it was shutting off at random times, then it wouldn't turn on at all. He had another friend take it to look at it, but he didn't do anything (as far as either of us know). I took a look at his house, when you turned it on the PSU fan wouldn't run, and the CPU fan would just twitch, then stop. I assumed it was a faulty PSU (400 watt, no name brand). He bought a Antec Earthwatts 650, and I installed it last night. When I powered it up the CPU heatsink fan spun for about 1 second then popped and started smoking, and the whole thing shut down. (also heatsink/fan seemed to be no-name brand, it didn't look like stock Intel - they typically have Intel branding, but it's been a few years since I've installed Intel chips..)

Since I don't want to cook my friends computer, I'm at a loss. I removed the heatsink/fan (the fan definitely smells cooked) and the cpu and motherboard look fine, no scorch marks or anything. Should I just have him get a new heatsink/fan, or is this indicative of a bigger problem? I don't want to try turning it on again, since I'm worried about cooking other parts if it's a PSU problem.

Any help would be appreciated.


----------



## Wrench97 (May 10, 2008)

Power supplies when they fail can often over-volt and damage other components.

What model Gateway is it?

Is the heat sink held on with screws/nuts, or the Intel style push/twist locks?

I would clear the CMOS, and try another fan on the board, now that you have removed the heat sink you'll need to clean off the old thermal paste/pad and install new> Arctic Silver Incorporated - Route to Product Instructions for Arctic Silver 5


----------



## grinkyfizz (Jan 13, 2011)

It's a Gateway FX7026. Here's the Gateway page for it.

The heatsink was attached with phillips head screws, it screwed right into the motherboard.

So you are thinking that the new PSU is faulty? So should I have him return/exchange it or is there a way I can test the PSU without potentially breaking anything else?

Yeah, I'm definitely doing the whole new heatsink/thermal paste, since the paste left on the chip was pretty dry and crusty.


----------



## Wrench97 (May 10, 2008)

I referring to the original PSU failing not the new one.

The best way to check the power supplies is with a digital voltmeter, it's also possible the fan was failing on the heat sink causing the CPU to overheat and shut the PC down was the original problem.

I'm not familiar with that model but it should be a G33 Intel board the heat sink will use the standard mounting hole pattern but the back plate is not standard Intel, is the fan removable from the heat sink? can you get us a image of the fan/heat sink assembly?

 Test Your Power Supply


----------



## grinkyfizz (Jan 13, 2011)

The heatsink is mounted with screws in four corners, I'll try and get a picture, but since it's at his house I probably won't have the opportunity to take pictures until Friday night.

The fan does detach from the heatsink, it snaps on the top of the sink and looks like it blows down. It's basically a case fan, but the plug is a small 4 pin that plugs into the motherboard.

If the fan was failing on the heat sink, wouldn't the computer still have powered up (or at least the old PSU fan started spinning)? With the original PSU in, when I turned on the machine the only thing that happened is the heat sink fan gave a feeble twitch, then nothing.


----------



## Wrench97 (May 10, 2008)

The old PSU is probably a multi-rail 12v with low amperage on the rails, the fan shorting may have shut down the PSU, the new PSU single rail high amperage would not have shut down thus the smoke. 

I realize how the heat sink mounts, trick is to find one that will use that mounting without having to remove the motherboard and separate the back plate from the back of it to install one of a different style.


----------



## grinkyfizz (Jan 13, 2011)

Ok, I gotcha now. I didn't even really consider that the heat sink hookup would be non-standard. I'll try and have pictures as soon as possible. Thanks for all your help!


----------



## grinkyfizz (Jan 13, 2011)

Here is the heat sink with the fan removed, the fan is the same size as a standard case fan, but it has a plug with four wires going to the motherboard. Is it a specialty fan, or would it be ok to just remove that plug and attach it to a case fan? I see that most case fans have only three wires, so I'm guessing that it's not possible, but maybe I'm just looking for the wrong type of fan.









Here is the processor and the mount where the heat sink screws in.


----------



## Wrench97 (May 10, 2008)

That's called a PWM(pulse width modulation) fan>  PWM Fans

Looks like 92mm? Measure it to be sure if it's 92 or 120mm. Also the label should have the rated RPM listed.


----------



## grinkyfizz (Jan 13, 2011)

Ok, the fan does not list the RPMs, any suggestions?

This is what the old fan says:

AVC
model: DS08025R12UP
DC 12V --- 0.7A 026
HYDRAULIC BEARING

Thanks!


----------



## Wrench97 (May 10, 2008)

Looks like it's a • 80x80x25mm, • 4600 rpm, • 64 cfm
AVC DA09025T12U 90/80mm x25mm PWM LGA775 Round CPU Fan


----------



## grinkyfizz (Jan 13, 2011)

Ok, my friend is not to enthusiastic about ordering from a place called 'the fan van', and is now thinking about getting a new heatsink/fan combo. Would something like this: Tigerdirect Zerotherm fan work? It looks like it screws in and is in the right orientation to fit on his mobo.

Thanks.


----------



## Wrench97 (May 10, 2008)

That is made to have the black plastic brackets under the motherboard to attach the screws to, I'm not positive your board has a bracket, most OEM PC's attach the fan through the board to the case motherboard tray, you should however be able to modify the mount to use the existing screws to mount it.

Or he can contact Gateway and buy it from them.


----------



## grinkyfizz (Jan 13, 2011)

Would it just be easier then to buy one of the PWM fans off Newegg, even if it isn't the same model? Say like this one - Gelid 80mm?


----------



## Wrench97 (May 10, 2008)

They run a slower RPM and don't push the same CFM of air.


----------



## grinkyfizz (Jan 13, 2011)

Ah, it'd help if I was paying more attention, I suppose.

The problem with the fan you've showed me is that it is circular, so it wouldn't fit on top of the heat sink. The fan snaps into place on the top by four clips, they hug right on the square part of the fan.

The only fan I can find around that looks like it pushes even close to the same amount of air and is in the right shape with a four pin connector is this one:

Dynatron Top Motor

I didn't see anything at the Fan Van, and nothing strong enough at NewEgg or Tigerdirect (well, with the exception of the Vantec Tornado, which is a beast, and looks like it might be a little loud).


----------



## Wrench97 (May 10, 2008)

That one may work if the pc isn't pushed, but it won't supply the same cooling ability. the one at the fanvan is the same part number as the one you removed, the clips are out by the screw holes so I'm pretty confident it would attach.


----------



## grinkyfizz (Jan 13, 2011)

Well, he bought the fan from the fan van. Unfortunately it was 90mm instead of the 80mm of the original fan. With some creative work we got it attached to the heat sink (since the four notches lined up, just the fan went a tiny bit over the edges).

So, moment of truth, we plugged it all in and powered it up. Fan started spinning, everything was looking good, and then on the motherboard where the built in video (vga port) and usb ports are starting arcing and you could certainly smell smoke. (nothing was plugged into these ports, the only thing plugged in was the psu actually)

So now we're thinking that the whole motherboard is boned. This is just so weird. One of us must have gotten cursed or something.

Any idea why this would have happened?


----------



## Wrench97 (May 10, 2008)

The fan shorting out probably burnt the motherboard traces.

You need a board. It's a mAtx G33, the original Gateway replacement will probably be around $150 a Retail G31 about $50 but you'll have to deal with reactivating windows if you change out the OEM board.


----------



## Rich-M (May 2, 2007)

Wrench is right as if you change the board then the oem license for Windows is not usable and that adds at least $100 to the project. Unles the case is really desirable it makes more sense to buy a new case, system board and use the cpu and memory which you can do under $150 unless you can reuse the jumpers i.e. power, reset , etc...then upgrade board, cpu and memory makes more sense. It all depends what they can spend.


----------



## grinkyfizz (Jan 13, 2011)

Yeah, once we realized that the mobo was probably fried, he started considering a new case as well, since that case is slightly smaller than a mid-tower and it is a little cramped inside. Of course, money is an issue, and since it's been such a fun journey of 'what can break now?' he just can't wait to find out if he invests another 100-200 bucks only to find something else that doesn't work, like the processor.

The good news is that he already bought a new copy of Windows 7 (not upgrade) when he started out, because the previous guy who was helping him thought it was a hard disk problem so he figured his Vista install would be gone and he doesn't have any system restore disks (Gateway wanted to charge for them), he also bought a new hard drive back then as well.

So he's thinking about getting a new case, motherboard and heat sink (since the old one is cobbled together, and potentially screws into the case), so in the end he will have purchased Windows 7, a 1tb HD, new PSU, a fan, and now a mobo, heatsink and a case. So overall not the most efficient computer fix. Even though at this point it seems like getting a newer motherboard, processor and RAM seems like a viable idea, I'm pretty sure he doesn't have the money to lay out for that sort of upgrade. 

Just looking through the G31 boards and mid-tower cases, it looks like it won't be too bad financially, though I guess it's all a matter of perspective, given what he's already invested.


----------

