"DCIFRTHS" said:
I have a P4T-E that currently has a 2.0 GHz CPU. I want to swap in a 2.5 GHz
CPU, but I have a concern. This board is an Socket 478, and the stock Intel
heatsink and fan create a bend in the motherboard, below the CPU, when
properly installed. Too much of a bend in my opinion, but that's the way it
was designed
If I remove the heatsink and fan, the motherboard, under
the CPU, will first "unflex" and then "reflex" after installing the new CPU
and heatsink fan. My concern is this: Is this flexing of the motherboard
enough to cause any damage to the motherboard itself? Maybe damage the
traces between the layers? Any other damage that I am not think of right
now? I believe that I have replaced the CPU once before.
Thanks for any opinions you may have on this subject.
This document will give you some background.
ftp://download.intel.com/design/Pentium4/guides/29072801.pdf
Does your motherboard have a backing plate underneath the socket ?
This product, for example, uses screws and a backing plate, to
provide a little more support for the heatsink. It is possible
that more recent boards have that kind of plate as well. (Maybe
my P4C800-E has that on the bottom - it has been a while since
I've had it out of the case. I didn't have a lot of reason to
look at the bottom of it.)
http://centrix-intl.com/details.asp?item=4zxxzP4Retention-478
Now, if you were to use the kit from Centrix, with your retail
heatsink, be aware you would be changing the spring constant of
the board, and causing the cams on the Intel retention mechanism
to apply more force than normal. When you re-engineer a
mechanical solution, you own all the issues
Another approach to this, is to leave the stock retention plastic
piece in place, and buy a Zalman 7000A-AlCu as your heatsink fan.
It comes with a FanMate, to set the fan speed (and the fan is
pretty quiet no matter what setting you decide on). The Zalman
uses two screws, to pull the heatsink down, and apply a normal
force onto the processor. If you don't do the screws up all the
way, you can "tune" the amount of force used. According to Intel,
not as much normal force is required, when using thermal paste,
as opposed to a phase change compound. The degree of force needed
is also determined by the need to resist shock and vibration,
and if you have the PC in a safe place, and don't plan on shipping
it anywhere, then again, less force could be used. (Remove the
heatsink before shipping the PC.)
As for solder joint reliability, in fact there is a lot of concern
in manufacturing PCBs with BGA devices on them (like the MCH). Some
of the unique looking ball patterns on the bottom of high ball count
BGA packages, were invented to relieve stress on critical rows of
balls. When I see what the CPU heatsinks do to my motherboards, like
you, I feel a concern, but looking at the Intel slide set at least
gives the feeling that someone has looked at the issues. I'd be
even more comfortable, if they stated what they thought the expected
motherboard life was, with that amount of bending.
You might look around some of the heatsink/fan review sites, for
a heatsink that still uses a retention plate. Maybe there are still
some for sale somewhere. I've seen heatsinks that use four screws
and springs, and a backing plate, to allow finer control by the
user of the install. But, they don't sell well, due to the need
to remove the motherboard from the case, to do the initial backing
plate install.
This one looks like it is built like a tank:
http://www.overclockers.com/articles798/
This page has a performance chart:
http://www.overclockers.com/articles373/p4sum.asp
And this one lists the articles on the site:
http://www.overclockers.com/topiclist/index15.asp
Have fun,
Paul
