On 14 Jan 2002, at 12:18, Mary Conner wrote: > Laptop fans don't seem to be very durable.
Fans in general? I've had very little trouble with CPU fans (fortunately - and perhaps I'm lucky) but I find failed PSU fans and noisy (vibrating) case fans to be just about the commonest faults on desktop systems. I have a lot less to do with laptop systems, but so far (touch wood) I've no experience at all of laptop fan failure. > I have a two year old Dell > that has apparently had a broken fan for a long time, and I didn't notice > it because the it (either the MB or the Celeron) throttles down > automatically but continues to work and nothing I was doing was that CPU > sensitive that I would notice the lack of speed. This is actually kind of > neat because it leaves the computer still usable (and even at top speed > with an external fan blowing in the intake port), but I do wish it would > popup a notice that the CPU was being throttled. My Tosh 4070 makes it quite clear that the fan is running - it's LOUD, several decibels more so than the average desktop. Small diameter fan running at high speed = fast air flow = aerodynamic noise. Many ancient laptops had a two-colour LED which shone green for full CPU speed, red for reduced CPU speed (though you had to select the CPU speed manually, using software or by a special key combination). The extra manufacturing cost of fitting this to current systems would be very small, though the introduction of technologies like "Speed Step" would complicate matters to some extent. Possibly a tricolour system would be needed. C'mon, Toshiba et al... Anyway I guess that's another reason for running Prime95 - you should notice a performance loss if your processor drops into a throttled mode for some "mysterious" reason! > > Yes, I do not think most laptops are very durable. Companies know they > will usually get a lot less use than a desktop, so they know they only > need to get a few months of actual runtime to get them out of the warranty > period. I think it has more to do with simply using them 24/7 (or more > than a few hours a day on average) than with prime95. Intermittent operation costs reliability - if parts are constantly being warmed & cooled they _will_ age. Also the average laptop gets dropped, rained on, moved from warm to cold environments, etc. etc., far more than the average desktop system does. > > Thermal protection for P4's is partly a matter of the chip, and partly a > matter of the motherboard/chipset. Intel built motherboards have been > shown to be very paranoid about throttling the CPU compared to boards > built by other vendors (and with non-Intel chipsets). Intel's BIOS doesn't even give you the choice of overriding the factory default throttling mode / thresholds :( > As far as the CPU's > own thermal protection, Intel took some heat for the fact that the thermal > protection was causing performance problems compared to AMD chips. This should not be a problem - provided it is actually possible to get the heat generated out of the chip without tripping thermal protection, with a properly engineered and assembled heatsink / fan / case ventilation system. > There > was a rather famous test done by Tom's Hardware Guide where they removed > the heatsink from test chips while they were running to simulate a > catastrophic failure of the heatsink falling off the CPU. Ever heard of a heatsink _accidentally_ falling off a CPU on a running system? Sounds about as probable as an airline passenger being killed in flight by a meteorite strike which doesn't bring down the whole aircraft. I thought the point of the THG "test" was to educate self-builders using Athlon/Duron not to test a system by applying power - even for a few seconds - if the CPU heatsink wasn't fitted. Anyway, the latest AMD processors have thermal protection against this sort of abuse. > The P4 > throttled perfectly with a huge performance degradation, but it kept > going. So it does seem odd that your chip would have "burned", but > perhaps Intel backed off on the thermal diodes in the chip itself because > of the performance problems. I doubt it. If they were really worried they'd just have disconnected the sensors. There seems absolutely no point at all in fiddling around with thermal protection if you leave yourself with a product which is subject to both thermal performance degradation and rapid failure due to moderate overheating. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
