how much pressure needed for wb hold downs?

can someone tell me if I'm doing this right?

I tried my to mount my cpu wb and I thought I had it clamped
well. I started the pc and it shut down after about 10 sec. I checked and re-seated the wb and tried to boot again. this time it shut down after 5 sec.

My diy clamping system may be at fault.

How much pressure is needed for the cpu wb? I see a lot
of hold down systems with springs. What is the spring rate needed?

I went back to my Vantec copper flower, reset my cmos and it booted right up.

Please help as I'd like to get my cooling rig set.

VBallCoach

What are you mounting (P4, amd?) and how (socket clips, 4 mobo holes, P4 mount?)?

AMD specs mention a max of 30 pounds of pressure on the top of the die. I'd go for 20-25 pounds of total pressure.

I'm using clips as my AMD MSI K7N2-L doesn't have the 4 holes..

will do a push-test on my springs with meter to see if they're within specs.

I remember you making rotor-type blocks. If the total thickness is close to 1/2 inch, you could easily use the swiftech socket A clips like on the mcw5000 and 5002 blocks. Look at this picture for how it works.

http://www.swiftnets.com/assets/images/products/MCW5000/springs-installation.jpg

The overall copper thickness is 1/2 inch. The spring over the cam box is weaker than the one close to the die; this makes the pressure equal from both sides. You wouldn't have to tap the copper block if that was a problem. Just drill a hole the size of a #6 screw for each mount and use a #6 nut on the top side of the block. PM me for more details if interested.

Also maybe check how it's being mounted to make sure it isn't shorting something out. Seems a bit weird it stops working after a few seconds but works when you go back to your old heatsink. Be careful not to apply too much pressure though since it's an AMD chip; I used to have nothing but bad luck breaking/flattening cores!

I have a P4 mounting bracket and clamps from Swiftech... It required so much force to clamp it on that my thumb hurt ALOT... But ive also heard that Swiftys require far more force than other clamps... So working on that... I would recommend just buying a set of clamps

I'm gettin ready to install 3 rotor style blocks in my case, and to mount them I'm using #4 threaded rod, nuts,washers, and I went to staples and bought some cheap mechanical pencils and I'm ripping the springs out of them. Should provide just enough force, and keep everything nice and level.

-Andy

I experimented with adjustable, spring-loaded clamps. I've only worked with P4s, but I found no measurable improvement in temps beyond 20 pounds of holddown force. Of course, that was with good quality, carefully applied thermal grease. However, if you have a thick grease layer and it doesn't flow well, you'll need more force and/or time for it to settle out ... sometimes, just to test the theory, I would apply a big blob of grease, increase force to 30 pounds initially, let it heat up, let the grease flow, then back off to 20 pounds and it would work just as well.

I think socket 478 P4s can handle more force than that ... maybe up to 40 pounds?? Don't quote me on that, but I remember seeing pictures of bending mobos on the Intel developer site saying this was "OK" and "expected"!

I've read the Athlon 64 has an even higher clamp force designed in, which is why they install a support brace under that mobo to stiffen it. Bottom line, 20 pounds is a reasonable compromise and starting point that should not hurt your cpu case and still give decent thermal contact. Good luck.

KK

thanks all!

gungeek, thanks for the clips.