How long would it take???

Hello all,
I am wondering what would be the average time it would take a computer to fry the processor (and other key items) if the cooling fan would die on it. The processor is a Pentium 3 933mhz dell. Please assume all fans would die at the same time. Thanks

 

When you're talking of speeds like that, if the CPU fan dies, it'll take about 2 seconds to fry the CPU.

If the power supply fan goes, your guess is as good as anyone else's.

 

Hi,

Intel cpus are a little more forgiving than AMDs. I have heard several stories concerning AMD T'birds where the user saw that the fan was not spinning on the initial boot up of a new system and could not reach the on/off button fast enough to save the cpu. Todays cpus just produce too much heat to function very long w/o a properly operating heatsink/fan.

Tin

 

Thanks All

 

Interesting related information.

Intel's series of processors has as a standard feature the built-in thermal diode that with the appropriate support on the motherboard prevents the processor from burning out due to high working temperature. The diode would momentarily detect any significant jumps of the temperature and would automatically bring down the working frequency and shut down the system. There was no such mechanism on the AMD Thunderbird and Duron processors, so it happened that if the cooler was not installed the right way these processors would go out in flames (not literally, but close). Thermistors and thermo diodes on the motherboards were simply to slow and they couldn't substitute the on-processor thermal diodes. AMD AthlonXP has the thermal diode in the processor's core and the temperature values are acquired through two of processor's pins - anode and cathode. They're used together with the external electronics, with which the system for protection from the "thermal processor's death" is completed. Big problem is to change the habits of the motherboard manufacturers that are used to not using special electronics in motherboards for AMD's processors. That is the thing that started the whole discussion revolving around Dr. Tom's test. By using a motherboard that didn't posses the electronics that takes advantage of the on-processor thermal diode and reacts accordingly to the data acquired from this diode, the conclusion was made that AMD's thermal diode reacts too slow and that the processor doesn't survive the "heat blast ". The truth is quite different as a matter a fact. The main party to be blamed here is the motherboard manufacturer that didn't build in the needed electronics and therefore didn't support all of the capabilities of the Athlon XP generation of processors. AMD reacted to this and motherboard manufacturers should be adding support for this more advanced feature on their newer models. Although the intention was to discredit AMD's new product the overall effect was positive, because this will make motherboard manufacturers to pay more attention on monitoring section's design. It wouldn't be bad if you would check with your local computer hardware salesman if the motherboard you plan on getting has this kind of protection mechanism or not!


Above excerpted from here.

 

Sorry, to burst any bubbles but real world experience is more useful here than theoretical. I ran a 1.2G Tbird for about 2 hours with the cpu fan disconnected before noticing the cpu temp was 69C. I had accidently disconnected the connector when messing around inside the case. I simply reconnected the fan connector and booted up to let the fan cool down the cpu quickly. My system is now working just fine again.

The "instantaneous cpu death" we hear about is when you don't have ANY heatsink attached to the cpu. And I too have heard that you'll never be able to rip the power cord out fast enough to save the cpu.

 

I don't buy the "Instant Fry" either.

Having been involved in heat exchange R&D during my working days I am not easily convinced about such rapid heat gain rates versus the driving power available. It would take pretty steep ramp up times to accomplish permanent damage, which usually would mean temps in excess of 100 C. The red line on most processors is somewhere around 80 C. but permanent damage come somewhat higher. With an ample sink attached, I can believe you may operate well below 80 C. in a normal ambient of 22 C. but I don't think I'll test that theory. I'll take your word for it Chiles4

Edit, Let me give you a "Fer instance" I plug in my 300 watt soldering iron and it takes it over 2 minutes for it to reach "spit frying" temperature (100 C.). That would closely approximate a microprocessor pumping into a dead short and being powered by a 300 watt supply. Now most processors won't be running short circuited and will normally dissipate less than 100 watts. Now physics and heat transfer being what they are, the terminus temperature with a sink attached and the fan shut down won't likely fry it instantaneously. Perhaps whoever made that statement had other problems such as a dead short on the MOBO that caused the processor to pump into a dead short. That may well explain why the fan wasn't running. It didn't have any voltage available since the short circuit clamped the voltage to ground potential.

 

Here is a little story from tweakmax.com that details a water cooling experiment gone bad. Seems that they didn't get good contact between the cooler and the CPU. THey fried their 1Ghz T-bird in seconds.

Frying an Athlon

Hex92

 

That's amusing.

Thanks for sharing that hex92. (that's 146, your age or IQ?) I think the moral might be , operating a CPU on a T-bird at over 1 gig and not having the heat sink mounted properly is disasterous.

I didn't see the mention of any heat transfer enhancing compound having been used either.

I do agree with their comment as pertains to springs used instead of screws. Here's why. If the sink is ridgidly mounted with screws, it will expand and stretch the weakest link in the mounting system when it heats up. Then when it cools down there will be an air gap and the heat transfer will be much lower. In time the CPU will fail, just as the one did in their test, because it in effect has no heat sink in contact with it when cold.

Mounting it with springs will allow for that expansion and then still maintain the same pressure when it cools down. Dynamic mounting is very important under conditions like this. I have seen thermal expansion actually snap machine bolts made of hardened steel (8 point). The laws of physics are never wrong, most common materials expand when heated and contract when cooled. There is no immovable object, that has been established also.

I don't know if we can trust the folks you cited to give us any meaningful data from their test methods. Whattauthink?

Best regards

 

I think you've found a platform from which to preach.

Also the older you get, the better you were.

 

Yeah man!

And the faster I used to ride that motorcycle!

 

I saw a video of this.

First they took an Intel 1G. In the background was a monitor running Unreal Tournament (or something like that), in the foreground was the MOBO with CPU and heatsink visible and a digital temperature gun aimed at the CPU. As soon as they removed the heatsink you could see the game slowing to a crawl, the CPU smoked a little after about 5 sec but it kept on going. Temp ran to multiple 100's of degrees then cooled off as the pentium cooling took affect. Eventually they replaced the heatsink (no fan), it cooled off and speed right up.

Then was the Athlon 1.2G. Same setting. Temp ran to over 600 degrees F. Game stopped. Smoke. Then flames. All in about 5-10 seconds. Cool video.

 

I saw the AMD "reply" video which showed a Q3 demo playing on an AMD XP on a board that supported the XP's thermal monitoring. They disconnected the fan and the game demo just kept on going. Then they pulled the whole HSF off and the machine simply did a shutdown. Cool idea - too bad so few boards support it.

 

I had a 900-MHz Slot-A, processor with a massive heat-sink until just last week. About a year ago, I noticed the fan on the heat-sink wasn't working. I realized it had been that way for several days. (I don't run a closed case--ever.) The heat-sink was massive so there was no damage and never even a lockup.

Of course, the 900-MHz chip isn't as fast as some discussed here. My point is that one should get as massive a heat-sink as one can find. Frankly, I wish all processors had heat-sinks large enough that fans weren't necessary at all.

 

Another "Real World" experience by a "system builder" of the most inexperienced kind. I did build last fall a sys. with AMD 1.2 and upon initial power on with an open box, I saw the "came in the box fan/hs approved by AMD" wasn't spinning. This didn't last long-maybe 15 seconds or so. My reaction was and knowing not much about anything felt the h/s and no obvious heat to the touch. I tried another coupla times with no luck then spent the next day or so checking to see if the system had a thermal "kick in" which of course it doesn't . Got a response from AMD that prompted me to press firmly on the hub of the fan and this corrected a neglected step in the assembly,thereafter all worked well. Moral is that I went well beyond the "fries in seconds" a couple of times and supports aforementioned thought of even without fan spinning, the h/s will handle it beyond the point I had been warnedof so many times.

 

Wow, guess this teachs me to site anecdotal evidence But to tell you the truth, I hope I will never be able to site first hand experience with this.

Tin

 

My mainboard has an option in the CMOS that will sound an alarm if the CPU reaches a certain temp and then shut it down if it gets hotter. Is this a good option, or not fast enough for a Tbird?

 

I have the same sort of setup on my IWILL KD266 motherboard.

The motherboard cd also included a utility that runs from within windows that shows me my current fan rpms, temps etc. It can be set to update between 1~6 seconds. It sounds a piercing alarm through the pc speaker and a prompt on the screen if the fan(s) rpm dips below a preset speed or temps get to high. After that it shuts down if the temps continue to climb and reach X degrees F.

I'm not sure what the lag time between the thermal sensors on the processor, mboard and software is but I think as long as the heatsink is still in place it should protect me from grilling my T-bird.

On the less scientific side, the Thermaltake Volcano 6 fan/heatsink that's on my T-bird generates such a noisy airflow that I'd know if the fan failed ---- The system would actually run quiet!!

Gary

 

The options in the bios to shut down when temps get too high is not for a "meltdown" situation. It's for a gradually worsening situation. It will work say if your HSF fan stops spinning but if the heatsink is dislodged from the cpu your bios wouldn't have time to save you.

But I guess that's been changed somehow with motherboards that support the XP thermal diode.

 

ASUS COP

My new computer has an ASUS A7V333 MoBo (with an Athlon 1800XP). Supposedly it has something called CPU Overheating Protection (COP). Its not mentioned in the manual but on their website it says it
" is a hardware protection circuit that automatically shuts down the system power before temperatures go high enough to permanently damage your CPU. "

Of course I have no idea if it would protect my machine in the case of a major temperature spike. ANd hopefully I won't have to find out

Hex92