Dell GX 280 - Heatsink not making contact

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brockalee

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Working on a Dell GX-280. It won't POST unless I take the fan off and bear a lot of weight down on top of the heatsink. Otherwise the fan starts ramping up to full speed.

It's doing just like this guy's computer.
http://www.youtube.com/watch?v=nS1x54K44WA&feature=related

Any ideas? There's no way to tighten anything. Dell made this so that the heatsink just goes under two plastic clips. I need to get this one fixed ASAP!

I actually tried replacing the heatsink with another of the same model, but same problem. How can I get that sucker tight! I don't have any copper shims. Would a... *gasp* penny work? Afraid of doing that though...
 
Try shimming out the ledges on the heatsink with a piece or two of duct tape or plastic or a metal shim cut from tin. Isn't there just one small tab on the board bracket, on each side? You also may not have enough thermal compound; you might try making it a bit thicker. And is the bracket nice and tight to the board?
 
100% Guarantee it is the motherboard that is bad.

I have had that EXACT same issue at work 30+ times in 2005-2007.


Each time the system was under warranty, and I physically replaced the motherboard myself (it takes 5 minutes) and the problem was resolved.
 
If im not mistaken those computers have like a plastic thing green.

Remove it and play with the heatsink... remove ram sticks and insert them

nudge the heatsink

and also look for bad capacitors
 
It will post if I put a LOT of pressure on the heatsink - otherwise it just keeps ramping up the fan speed.

So I know it's not a bad motherboard and the caps are fine. The memory isn't the issue this time either. :)

It's either an issue of the CPU not making sufficient contact with the board or the heatsink not making contact with the CPU.

I've tried folding some tin foil and putting it between the CPU latch and the CPU cover thinking it would put more pressure between the CPU and MB, but it still required a lot of pressure on the heatsink to POST.

You're right Jav - it does have two green clips on either side. They don't seem to make much of a difference though, off or on.

Some more background on the situation:

This type of sockets has pins and the CPU has flat contacts. When I removed the CPU initially, some dust, white flakes, and a small amount of thermal paste made their way into the pins. I removed the debris, but I might need to get back in there to make sure it's all in order. It could be causing some issues with connectivity now that I'm thinking about it.
 
The factory Dell Heatsink is perfectly fine. I have NEVER seen more than about one of those fail (get noisey from debris or bearings going bad).

The problem you have is NOT the CPU either or it would never POST.

The problem IS a bad motherboard. I have encountered this problem at least 30 times. Dell IS aware of the issue and offered replacement motherboards for this issue back in 2005-2006

The problem is NOT a loose fitting heatsink/fan... A normal one even if you were to install it without heat sink compound would POST and it would get much hotter than this! This is NOT an overheating problem... If it were, they would ALL have this problem; since, the heatsinks fit just as tight now as it was when new. The heatsink goes under little black, plastic tabs to hold it down.

The green clips pretty much do nothing. To remove a CPU cooler, you need only remove one of the two green clips then wiggle the heat sink clockwise and counter-clockwise (back and forth) until the thermal compound loosens up a bit. Now, pulling the black plastic tabs back lift the heatsink like turning a page in a book.


The ONLY recommended heatsink compound that is endorsed by Dell is ShinEstu MicroSi (they even provide it) with the replacement motherboards... Obviously Arctic Silver 5 (and others) would work just fine.


The problem is that the processor sockets occasionally go bad in these do to the excessive heat and ROHS compliant solder. It is NOT common, but the proper fix is a new motherboard. In this situation, if you push really hard on it you must get the LGA 775 socket to momentarily connect to the CPU and the system to POST.

Even if you get some aftermarket CPU cooler, you will need some aftermarket bracket to put more pressure. Directly under the plastic retention frame holding the Dell Factory heatsink/cooler is the metal from the chassis. You will NOT have room to install an aftermarket heatsink retention bracket!!! Clipping it in with the OEM retention frame won't do any better, either!

In other words, you won't be able to clamp more pressure on this socket very easily. Even if you do, it will encounter the same failure and then you will have a customer return.


You can get a refurbish board for $25... (eBay has them)

Here is how to change it http://support.dell.com/support/edocs/systems/opgx280/en/ug/sdabout0.htm#1053120


You can then set the Service Tag in the BIOS to that on the chassis
 
Last edited:
This... Except that that heatsink is for the socket 478. Otherwise exactly what I would've said were I not so lazy

NETWizz said:
The factory Dell Heatsink is perfectly fine. I have NEVER seen more than about one of those fail (get noisey from debris or bearings going bad).

The problem you have is NOT the CPU either or it would never POST.

The problem IS a bad motherboard. I have encountered this problem at least 30 times. Dell IS aware of the issue and offered replacement motherboards for this issue back in 2005-2006

The problem is NOT a loose fitting heatsink/fan... A normal one even if you were to install it without heat sink compound would POST and it would get much hotter than this! This is NOT an overheating problem... If it were, they would ALL have this problem; since, the heatsinks fit just as tight now as it was when new. The heatsink goes under little black, plastic tabs to hold it down.

The green clips pretty much do nothing. To remove a CPU cooler, you need only remove one of the two green clips then wiggle the heat sink clockwise and counter-clockwise (back and forth) until the thermal compound loosens up a bit. Now, pulling the black plastic tabs back lift the heatsink like turning a page in a book.


The ONLY recommended heatsink compound that is endorsed by Dell is ShinEstu MicroSi (they even provide it) with the replacement motherboards... Obviously Arctic Silver 5 (and others) would work just fine.


The problem is that the processor sockets occasionally go bad in these do to the excessive heat and ROHS compliant solder. It is NOT common, but the proper fix is a new motherboard. In this situation, if you push really hard on it you must get the LGA 775 socket to momentarily connect to the CPU and the system to POST.
Click to expand...
 
SmithFamilyDesigns said:
This... Except that that heatsink is for the socket 478. Otherwise exactly what I would've said were I not so lazy
Click to expand...

NO, they are LGA 775. I have done 30+ of these and remember! The GX280 is Dell's first Business Computer in the OptiPlex line that used the LGA775... they also all came with SATA hard drives and the GX270 systems came with PATA drives (though there was a SATA port on GX270s)..

GX270: PGA 478, these used 8x AGP, and they usually shipped with PATA drives though they have a SATA port... They use DDR 1

GX280: LGA 775... These were the first OptiPlex systems to feature PCI Express, and they typically shipped with SATA drives... and they were the first to feature DDR 2

Here is a picture of a GX280 board right out of a cardboard box:
ports800.jpg


This is what the boards look like:
http://support.dell.com/support/edocs/systems/opgx280/en/ug/replbrd0.htm#wp1115023

In both of these, you can clearly see they are LGA 775.

These are the form factors of GX 280 systems:
http://support.dell.com/support/edocs/systems/opgx280/en/ug/index.htm

Identify the case, so you know which motherboard to order. I worked on the Small Desktop Computer form factor of the GX280 systems.
 
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NETWizz said:
NO, they are LGA 775. I have done 30+ of these and remember! The GX280 is Dell's first Business Computer in the OptiPlex line that used the LGA775... they also all came with SATA hard drives and the GX270 systems came with PATA drives (though there was a SATA port on GX270s)..

GX270: PGA 478, these used 8x AGP, and they usually shipped with PATA drives though they have a SATA port... They use DDR 1

GX280: LGA 775... These were the first OptiPlex systems to feature PCI Express, and they typically shipped with SATA drives... and they were the first to feature DDR 2

Here is a picture of a GX280 board right out of a cardboard box:
ports800.jpg


This is what the boards look like:
http://support.dell.com/support/edocs/systems/opgx280/en/ug/replbrd0.htm#wp1115023

In both of these, you can clearly see they are LGA 775.

These are the form factors of GX 280 systems:
http://support.dell.com/support/edocs/systems/opgx280/en/ug/index.htm

Identify the case, so you know which motherboard to order. I worked on the Small Desktop Computer form factor of the GX280 systems.
Click to expand...

Good info, thanks! :cool:
 
Vicenarian said:
Good info, thanks! :cool:
Click to expand...

The key is to get a good GX280 motherboard for $25 that works perfect and doesn't have bad capacitors... and match the form-factor; since, there are probably at least three different part numbers depending on the chassis.

If you can get the part for $30 after shipping, you could easily pass it onto the customer for $50 for the part and $70 or so for the labor...

They will be VERY happy if you fix the problem for $100.


Tech tip: Set the Service TAG to be the same in the BIOS before booting the PC. If you do, Windows will query the system and see the EXACT same motherboard... If you don't Windows Vista/7 in particular will KNOW you changed the motherboard and ask you to re-activate.
 
Great info guys - thanks so much. I went ahead and swapped the computers for the customer so I have the bad PC now. I'll probably get another board and fix her up.

I agree about the socket being bad and I don't mind replacing the MB, it just became more about learning why it wasn't working than getting it working... if that makes any sense. :)

Thanks again!
 
NETWizz said:
100% Guarantee it is the motherboard that is bad.

I have had that EXACT same issue at work 30+ times in 2005-2007.


Each time the system was under warranty, and I physically replaced the motherboard myself (it takes 5 minutes) and the problem was resolved.
Click to expand...

I agree, DELL's are notorious for this issue, they have no fix. I have found that replacing the Fan with a new one makes no difference at all, it is a Motherboard issue.
 
Make sure there aren't any "short" pins under the CPU for starters (all uniformly the same size). And I disagree with adding too much thermal paste. That WILL make it run hot. A little dab will do. Trust me! Too much and the heat can't transfer very efficiently.

Good Luck! :)
 
What's to disagree with? If it's "too much" or "too little" or whatever, then obviously it's no good. The bottom line is always what does what it's supposed to.
 
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