Bill Adams comments on HSF and waterblock testing

[Butcher_]

BigBen2k - how are you planning to attach the IHS to the slug? Solder?

[aicjofs]

For lab testing it presents quite the challange for sure, so many variables to control and some that are even hard to quantify. Definetly interesting read. Then there is real world testing. As noted there is quite a difference between product design testing and comparative product testing. When tough questions like this are brought up sometimes it is necessary to think outside the box and create a new scale for rating based upon the usual metrics. Obviously the usual units of measure are used in the lab for product design, and the new scale for comparative testing(At a cost of testing resolution but more meaningful to the consumer).

i.e. Grade B heatsink, S rating waterblock, this product scored a 6.7 on the "aicjofs scale", whatever brings a more meaningful quantifier to the average consumer. Me I like to read the hard data numbers, but I think I am a minority.

Getting a sector of the scientific community to agree on what criteria would yield what on the new scale would be almost impossible. Especially when pride, ego, and profit can influence the desire to adopt a new system, but often times once a few people adopt an idea others follow.

[BigBen2k]

Actually, it's not the block's flatness that's interesting, it's the testing device (heat die or otherwise). If it changes, then I end up measuring a new block in a different way. The effect is measurable.

As for the nickel coating, it's all about how Nickel is a harder metal than copper, which leaves me with a low maintenance surface (but I still have to check it). Using a bare copper heat die to test, I'd scratch up the surface in no time, just from the roughness of everything that I'm about to test on it, either as a scratch, or as an imprint. The Nickel plating is going to make it a lot more durable. Every time we mount a block, there's a good chance that we're changing the surface geometry, so it's got to be checked periodically. An easy way to check this, is to run a test series with a "calibration block" (a block of your choice) prior to each test run, to see if everything is running normally. You keep your calibration block, forever; it's your reference point. If you start seeing different results with your calibration block, then you can either adjust the test results, or send the die out for maintenance.

I don't know exactly how the IHS flexes, but I'm pretty sure that it does (to make a flat contact with the CPU core). The old specs for clamping force of an HSF were much lower, prior to the introduction of the IHS. What that translates into (to me) is that some of this force isn't applied to the CPU core at all. In what proportion is this force applied to the core? Only the designers know. Knowing that, and being limited by the lack of info, what I have left is ... an IHS capped copper slug. I'm sure I could clamp the whole thing down as much as I wanted, because I'm not going to be risking crushing a core here.

Right now I'm not sure what I'll be using for that TIM joint. A liquid paste is going to be variable, each time. An epoxy would be permanent (not practical). a TIM film product would be an easy solution.

As for the vacuum test, depending on the level of vacuum, I might have to plumb some hard lines. I'm not looking forward to that, because then I have no flexibility for the mount. I might be able to get away with high pressure tubing, dunno yet. Right now what's stopping me is the cost of the pump, and the safety of the vacuum chamber. It'll get done, in time. Got a little help from my friends...

I don't think that there's a need for a new scale. The basis on which everything is measured (in electronics especially) is usually provided by the manufacturer, following industry standards. In this case, the Intel TTV. Note though that there's been a progression in the proposed testing methods: the old testing method included modifying the cooling device, not the CPU, because that wasn't an option back then (no IHS). It was also more consistent with standard methods, because the temperature probe was exactly at the junction of the CPU and cooling device. Now, with the groove, the temp reading is (ever so slightly) recessed on the CPU side. The groove construction instructions specifically call for the temperature probe to sit at the bottom of the groove (on a step). That's not the actual junction... but it's pretty close.