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what happen to my motherboard and cpu?

by samokey / May 24, 2006 6:36 AM PDT

ABIT SG -80 SiS socket 775 MicroATX Motherboad
Intel Pentium 4 517 2.93GHz/1mb cache/533MHz FSB/OEM/Socket 775/ Processor

what would make the motherboad not work.
I put it together and nothing when I toke back a part the fan and the cpu had like wax on it?please help to understand this

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wont work
by rnl06 / June 2, 2006 5:39 AM PDT

You said you put together your computer and it wont work,do you mean nothing comes on?? any lights or beeps?? does keyboard lights come on?? make sure video card is installed correctly and any extra power cords to it? the wax stuff might be the thermal grease for heat conduction
when you turn the computer on does the cpu fan work?? also your power supply might be bad does that fan work on power supply??? just a few questions you could check

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thank you
by samokey / June 4, 2006 8:15 AM PDT
In reply to: wont work

I got it up and running thanks for the help

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I believe you to be in the deep end
by ChuckT / June 2, 2006 7:13 AM PDT

Please believe me, I am not trying to dissuade you from fixing your computer, and to learn about computers. But there are so many things that could go wrong, and so many routes to follow to resolve your possible computer problems that it is going to waste a lot of time.

It seems you are clearly in ''over your head''
Not to say that you won't eventually get there, to be able to take a computer apart, and put it back together, and to repair or replace just about anything in it. But that is not today, and not right now. You're asking questions that are so elemental, just shows that even to give good answers would require much more time and many more questions to be answered first, that this is just not the forum to do so.

Try and find some computer ''guru'' in your neck of the woods. Strike up a friendship. Buy him, or her, a Coke or Pepsi, and maybe a donut or two, and ask to look over their shoulder and ask questions every now and then. You, eventually, will start to pick up points, and learn through osmosis. Maybe even buy a book, or at least read a few computer related magazines.

If anyone here has the patience to talk (type) you through the problems, then they should be congratulated, with a special place reserved in that parts bin in the sky. But, really, the best help you could get right now might just be already living down the street from you.

Good luck in resolving your computer problem.

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Do you want to tell us the
by Ray Harinec / June 2, 2006 7:47 AM PDT

sequence you used or rather have someone tell you how you should have started????

That "wax" was likely from the thermal pad [improves heat transfer from the CPU to the Heat Sink]that was on the retail HSF that came with the CPU. It is called a "phase change" device. It changes phase from a solid to a paste when the CPU gets hot after the initial installation. Really not a good idea to reuse it. Must completely clean off both surfaces and put a fresh thin coating on thermal compound on it.

I'll tell you two things to do as a restart. Do them fine, no, them get other help.

First remove the mobo from the case, also the power supply. Lay the mobo on a piece of cardboard [insulator, the black pad that mobo came with is NOT an insulator!!!].

Unplug everything from the mobo, no memory, no CPU, no mouse, keyboard or cards of any type.

Plug the 20/24 pin connector and the 4 pin 12 volt connector from the power supply into the mobo. Plug the power supply in and turn the switch on its rear on. [might get an LED on the mobo to light, that indicates that the power supply is providing the 5 volt standby voltage to the mobo, the mobo uses this power to turn the remainder of the power supply on].

Now you will turn the power supply on by MOMENTARILY shorting the two Power pins on the mobo together. The only indication that the supply went on is that its internal fan will run and stay on. You can turn it off by the switch on the rear or by shorting the power pins far 4 or 5 sceconds.

If it works you know that part of the mobo works and it is not shorted out sitting on the cardboard.

Now you can plug in the CPU, memory while the mobo is on the cardboard. Much easier when the mobo has a nice solid backing. Then see if the mobo turns on agaion and HSF fan runs. That works you now can mount the mobo.

Here are the instructions on the proper way to mount a mobo, regardless of anyone else's opinion, including Linkit's.

You'll never find this in a book.

First note that the only mounting holes of interest are those with a gold ring [plated copper] around them. Understand that a mobo is a four layer board. Actually four layers of printed circuit artwork, each layer insulated from the other except where connections are needed. The connections are made by holes drilled through the layers and through the specific circuit leads that need to be connected. The connections are made after assembly of the layers by flow soldering in a solder bath and the solder plates through the holes, thus they are called plated through holes, before plating they are vias [can go from one layer to another VIA the hole].

Back to the mounting holes, one of the inner layers of the mobo is basically a ground plane with most of the ground [returns] wiring. Each of these mounting holes are plated through and connect to the ground plane, they are also continued through to the bottom side of the mobo.

The grounding of interest in this case is that of very high frequency signal and noise, not low frequency such as audio. For audio grounding the old single point grounding is proper. For RF [radio frequency] grounding, one wants to get as to close to an infinite equipotential surface as possible. Simply want the signal and noise level at every point to be as close to every other point as possible [of course we don't achieve that] as good practice.

Thus, for RF/EMI purposes we really want the mobo's ground plane to be RF connected to the mounting plate [thus metal standoffs used]. Again, good RF ground if made by the intimate contact of two mating conductive surfaces, NOT by screws. The sole purpose of the screws is to maintain the intimate contact. Good engineering practice never uses a screw to carry current.

Thus, for the mobo subject, the intimate contact is from the ring around the mounting hole on the bottom of the mobo, the surface of the hex standoff and the other end of the hex standoff to the mounting plate.

Now the kicker [many in the forums will say this is not so, however they are simply not correct] one usually gets what appear to be insulated washers with the mobo. In fact they are insulated, HOWEVER that is not their purpose. Remember that we want intimate contact which means that one wants to tighten the screws. However, the plated rings around the mounting hole are somewhat delicate printed lands, THUS the insulated washer goes under the head of the screw to prevent the tightening of the crew from damaging the printed ring.

Over the years I have seen people in the forums tell people to put the insulating washers between the mobo and the hex standoff. Just think about trying to accomplish that. They simply do not understand the subject of good RF grounding.

Now, many mobos will provide various types of plastic snap in devices. I never use them, however I can see where the mfr's are not going to try to take the time to get people to understand the subject The only penalty for using plastic versus metal is that the overall EMI performance of the system will be lessened. However, there really is no way that will be detected by anyone, thus the easy way out. I have talked to a tech that worked at a mobo mfg plant and he wasn't even aware that the mounting holes are grounded to each other inside the mobo.

BTW Intel has actually gone to 6 layer mobos in a few cases. Basically a layer is a fiberglass type material with copper plated on both sides and then etched for circuitry, thus it is two layers a second such board is then attached to the other through an insulating layer of something called prepreg and then squeezed extremely tightly. Imagine the accuracy needed to have all of the holes line up perfectly. It is really fascinating. When I worked on the Minuteman program we used 14 layer circuit cards. Note, always an even number of layers.

Regardless, If I twere you I would least use the metal mounts at the end of the mobo near the CPU and I/O ports.

The other related issue is that where one puts a new mobo into a case where a mobo existed before. In these cases, since not all mobos use the same mounting hole, it is not unusual for one to leave an old hex mount in at a place where the new mobo doesn't have a mount. This results in shorting out the good circuit artwork on the new mobo. Seen this in the forums a number of times over the years, however the classic was one where the individual mounted the mobo to the mounting plate with no spacers.

Hope that this gets you started on the right foot.

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(NT) (NT) Neat... Learn something new every day... Thanks
by billzhills / June 3, 2006 5:54 AM PDT

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