- Heat sink grease - 5 Updates
| dplatt@coop.radagast.org (Dave Platt): Apr 20 10:35AM -0700 In article <c3a729a6-4845-4c00-a524-a88dd8c2ff34@googlegroups.com>, > So conceivably couldn't they just not crank the clock to the max and save power and generate less heat ? Or >do they already do that ? My laptops have a setting, performance, balanced and battery life. Is that possibly an indirect "underclocking" >control ? If not, what is it ? Yes, almost certainly it is just that (and perhaps more as well). Most modern CPUs/motherboards/chipsets support multiple CPU clock rates - the CPU's own internal clock signal is created via a PLL/multiplier system, based on a slower fixed-rate crystal clock. The multiplier system is under processor control, so it's possible for the CPU to switch speeds "on the fly" (with a momentary pause while the PLL re-locks). I believe this is usually managed via the ACPI layer in the BIOS/UEFI. At the higher (user-visible) layer, this is usually set up via a performance setting of the sort you mention. The setting then controls a set of policies managed by the operating system, which specify when to change CPU clock speeds (and sometimes voltages as well) based on your usage patterns. "Battery life" would probably lock the speed at the lowest supported value, or at least to range of the slower values. "Performance" might lock it to the highest speed at all times. "Balanced" would either be a fixed speed in the middle of the range, or a dynamic system which increases the CPU speed in increments when the CPU is mostly busy, and reduces it when the CPU is idle more than a certain fraction of the time. On the Linux laptop I use, I have a choice of several such dynamic policies... some are more aggressive about increasing CPU speed, some are more conservative. The CPU speed can be varied over a range of about 2:1, on a per-core basis (and a core which is currently sitting idle isn't using much current at any clock speed, although consumption is less at the lower clock speeds even when idle). >capacitance. As such,lower clock speeds should be quite effective. If they could get it down to the point where no heatsink is needed at all, >wouldn't there be enough advantage in cost to justify a slightly lower clock speed ? A phone accessing the internet for example, how much does >that clock speed really mean then ? I am not being sarcastic here, that is a valid question, (I think) how processor intensive is all this ? Depends what you're doing. Just downloading a file is probably not CPU-expensive. Rendering a web page full of fancy animated graphics and video, considerably more so. Doing full-screen video may require little from the CPU, but may push the GPU quite hard (MPEG-4 or similar video decoding). Phones _tend_ to be designed to optimize battery life, as this is a key selling point... and so they'll be somewhat more conservative about speeding up their CPUs. And, phones do have heatsinks. They're called "hands" :-) |
| Clifford Heath <no.spam@please.net>: Apr 21 08:33AM +1000 >> an equal and opposite increase in clock speeds." >> I stopped all attempts at overclocking in the Pentium 2 days, but I grasp the concept. However, from what I have gleaned the processor speed is not the end of the world usually. In a PC for example the RAM is slower, the HD slower than that, and so on until we get to the speed of access to data sources, i.e. the internet. > OTOH the CPU does a lot more than the others. Sometimes cpu is the limiting factor, sometimes not. IMLE with clocking it did make a significant difference. I don't bother clocking now, but once it was a deal maker. The CPU chip's Front-Side Bus has been the main choke point for well over a decade. The CPUs already execute 40 instructions in the time it takes to fetch one, so faster internal clock speeds have limited impact. This is why the RISC/CISC wars of the 90s died out. It's all about bandwidth, not MIPS. |
| Jeff Liebermann <jeffl@cruzio.com>: Apr 20 06:56PM -0700 On Fri, 20 Apr 2018 07:37:13 -0000 (UTC), gregz <zekor@comcast.net> wrote: >good to try and achieve. I noticed some power modules were not perfectly >flat, and I started to sand them on a flat precision table. They were >pretty far off from flat. Nope. They might be warped on arrival, but are impossible to straighten without sanding or milling. Back in about 1976, we were having flatness problems with the transistors used in a linear power supply. There was a large extruded aluminum heat sink, and either 4 or 8 2N3055 transistors in TO3 packages. The heat sink was milled and quite flat, but the TO3 packages were warped from what I would guess was a worn stamping die. Some clever person in production decided that the cases could be straightened most easily by simply tightening the 6-32 screws holding the devices to the heat sink. After crushing the nylon shoulder washer, he torqued the hell out of the screw until the head broke off, and then gave up. The uneven squashing of the silpad insulator showed that the case was still warped. At that point, someone in production decided that I needed some unpaid overtime. It was now my project, errr... headache. I put together a dial indicator and verified that no amount of pressure from 6-32 mounting screws is going to bend the TO3 base when the spot welded lid was acting as a stiffener. Using a strain gauge, a bar of steel, and brute force, I determined that the best I can do with trying to straighten the TO3 packages was to bend ears near the mounting holes, making the flatness problem even worse. I fixed a few packages by milling the bottom of the package, but the cost was too high. Cheaper just to buy new transistors from a different vendor that weren't warped. The only good thing to come out of this waste of time was a fixture that I threw together to measure the flatness of the TO3 and later RF power transistor packages. It saved having the same problem repeat itself in later years. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| "~misfit~" <shaun.at.pukekohe@gmail.com>: Apr 21 03:13PM +1200 > stuff they make the heatsinks out of is very soft and the screws > might strip. The main thing is not to let it come up or move. If it > is done right they are usually stuck pretty good though. I've pressed very hard on some components, watched the compound come out all around then, on relasing the pressure to 'fastener pressure' have seen some of the ooze suck back in and sometmes air suck back in. Granted these weren't on ideal surfaces but since then, on those types of interfaces I let the fastener do the squeezing. > unfortunately lapping is simply impossible on most. I also agree with > Jeff Leiberman's caveat about making the surface concave. If you do > that it could be worse than not lapping at all. I have variously sized bits of glass that I use as backing for the wet'n'dry sandpaper that I use to ensure relative flatness. The glass isn't as flat as gauge blocks but it's sufficient. > caulking gun full of compound like this one place I worked. Makes it > easier to apply and I would never run out. They did but it took years > even with a bunch of techs working. For laptops, desktops and critcal ICs I use Arctic Silver. I bought a 'PC builders' size syringe of it. For less critical stuff I use either Electrolube HTC or, for 'cheap jobs' that need a lot of it and have large contact areas / raditaors (mostly aluminium LED PCBs to heatsinks), stuff I get from AliExpress. -- Shaun. "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM*." David Melville (in r.a.s.f1) (*Diagnostic and Statistical Manual of Mental Disorders) |
| "~misfit~" <shaun.at.pukekohe@gmail.com>: Apr 21 03:21PM +1200 >> If you need electrical insulation, petroleum jelly is probably >> better. The main objective is to fill the air gaps. > Petroleum jelly melts & runs. TMI. -- Shaun. "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM*." David Melville (in r.a.s.f1) (*Diagnostic and Statistical Manual of Mental Disorders) |
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