motherboard heatsink screws probably changes impedance

[darko_petreski]

I have bought p8z77-v motherboard and heat sink hyper t4. The heat sink uses metal screws and screw heads that are isolated from the board with tin mica insulators. But the screws are covering the copper wires on the board (do not know the name in English), thus changing the induction on some printed wires. The board wires are specially curved like stairs to calibrate induction and capacitance with each other, and I think this metal screws near them change their impedance. I am not sure how the screws of the heat sink will affect the motherboard but it is obvious that they will change the impedance of some of the printed wires.

Do you think that this is major problem and I should avoid this kind of sinks ?

 

[clutchc]

I am having trouble finding a good close-up of the back of the p8z77-v motherboard to see what it is that you are concerned the fasteners are effecting. If possible please post a clear close-up of the area of interest.

 

[darko_petreski]

I am having trouble finding a good close-up of the back of the p8z77-v motherboard to see what it is that you are concerned the fasteners are effecting. If possible please post a clear close-up of the area of interest.

To get the picture what I am talking about here is a part of the instalation manual of the heatsink:
https://docs.google.com/file/d/0B4lPhc2dLIYoUjNwMHEzSTJra3c/edit?usp=sharing

I made two images:
https://docs.google.com/file/d/0B4lPhc2dLIYoSjhQd2hfeGFBcTA/edit?usp=sharing
https://docs.google.com/file/d/0B4lPhc2dLIYoNWNBdHhTTUJkWG8/edit?usp=sharing

The first one is only with the screw attached. You can see that the screw is surrounded with flat copper on board wires (do not know the exact word in English) that are varnished/isloated. The original heat sink that comes with the processor uses plastic joins. But this one uses screws and screw heads because it is heavier. So as you can see on the second screen the screw head covers the wires, and changes their impedance.

I am 100% sure that this screws will increase the impedance for this wires and make it not equal with the rest of them, but my question is weather this can cause small slow down of the system even some errors.

Maybe this is more electronics question, but I posted it on electronics form and they closed the question saying that is is not electronic question (maybe electrical engineers do not know that impedance is or they thought it is agriculture )

I know that everyone installs this kind of heat sink like in the manual but I am not sure if outer motherboards has copper wires below the screw head.

 

[clutchc]

You're correct. The fasteners could be an issue if tightened too firmly and damage the insulation quality of the sealant over the board. Those "wires" are usually referred to as 'serpentine tracks'. They are used where equal track lengths are required with high-speed designs. So your theory about the possibility of shorting them changing the capacitive or inductive reactance would have value. On the other hand, I never heard of an issue with cooler mounting on any other MB. So, while I can't be of any help answering your question, I would think that a felt washer between the board and fastener would be a suitable solution to the slight possibility of possibly crushing the varnish sealant and making electrical contact.

 

[darko_petreski]

You're correct. The fasteners could be an issue if tightened too firmly and damage the insulation quality of the sealant over the board. Those "wires" are usually referred to as 'serpentine tracks'. They are used where equal track lengths are required with high-speed designs. So your theory about the possibility of shorting them changing the capacitive or inductive reactance would have value. On the other hand, I never heard of an issue with cooler mounting on any other MB. So, while I can't be of any help answering your question, I would think that a felt washer between the board and fastener would be a suitable solution to the slight possibility of possibly crushing the varnish sealant and making electrical contact.

Also I have not heard of an issue with cooler mounded on the MB to make a problem, but if it does probably we will never figure out what is causing it . This makes sense because the processor that comes with a heat sink has plastic joints. I am still skeptic that this metal fasteners can change the delay of the signal for those traces that are covered. I am interested how this is solved on mission critical servers.
But in eater case I will use another layer of felt washers to reduce the capacitance and inductance and hope there will be no "hidden errors".

Thanks for your response