...and again, that book was published in 1996, referring to late model AT systems that indeed had the PSU responsible for cooling. That doesn't authoritatively state that it has always been true or will always remain true.

No, but it shows the PSUs and the location of the fan on each used from the PC/XT onward.

Since when do the vast majority of systems have the CPU fan blow onto the heat sink? Again, this is not the way the "majority" of systems are built. Blowing the air onto the CPU is a relatively new thing and far from a "standard" method of cooling a system.

Do you honestly believe that? Seriously?
Since the introduction of the fan on CPU heatsinks they have blown on to the heatsink.*
There is a reason for that.

Take an average pedestal fan- stand in front of it. How far away till you no longer feel a breeze? Now stand behind it. How close do you have to be to feel any air being drawn past? How many metres (feet or yards) do you have to be from the fan to feel the equivalent airflow as when behind it?

Axial fans are great at blowing air over a small area. The air blown from such a fan extends out only a very small area from the edge of the blades, only a few degrees. But they draw air from almost every direction behind them.
Hence although you can feel a good breeze even a couple of metres away, you can't feel much air flow from behind unless you're almost touching the fan guard at the back.

For this reason the only heatsinks that use a fan drawing air are extremely low profile use as often used in server systems.
The heatsinks as used on normal systems have long fins- having a fan draw air through those fins would watse the majority of the surface area of the heatsink- it would have no cooling effect.
Having the fan blowing onto the heatsink makes full use of the surface area provided by the long thin fins.
Mounting a fan to draw air through such a heatsink is a great way to overheat the CPU.

* Yes there were a few early ones that drew air through the heatsink, but as blowing was more efficient, that's what they all ended up doing.

Some of them provide an extra fan at the rear & front of the case, but if you put your hand in front of the rear fan, and then in front of the PSU fan you'll find the PSU is the one shifting the most air, by a significant margin.

Again, incorrect. The exhaust fan clearly pulls out more air if it's doing it's job right.

Again, incorrect.
We're talking about a standard system, the sort built in the 10's of thousands, not something custom built with overclocking in mind.

If you have no alternative suggestions after being supplied the data, then it stands to reason that my conclusion must be correct.

Just because someone doesn't have an alternative suggestion doesn't make the current one correct.

And i would say otherwise because it flies in the face of my own personal experience & knowledge.

Your experience and knowledge seems to be limited. You still seem to think that the standard way of cooling a system has always been for the CPU fan to blow the air onto the CPU heat sink, which is incorrect.

I cannot in all honestly believe that someone that claims they have years of experience at building PC systems would make such an erroneuos statement.
As posted at the top of this post- that is the best method for cooling any heatsink with fins 10mm or longer- the fan blowing air through the heatsink. For cooling the system- the air through the PSU does that.

So we are still left with the opposite alternative of you refusing to accept personal testimony from a peer technician, hardware enthusiast, museum collector of PC hardware, and computer professional. What reason would someone have for refusing to believe this unless they were simply being stubborn?

The fact that you don't consider the PSU fan to have been the main method for cooling a system since the PC/XT era. The fact that you believe that the CPU fan blowing air on to the heatsink is something new.

In this case, blowing the air onto the CPU caused the failures that required components to be replaced.

Once again, claiming that the method that cools 100's of thousands of PC systems is something i can't accept.
Why it should work for all of them, and not that one just doesn't add up.

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Grant
Darwin NT

Your experience and knowledge seems to be limited. You still seem to think that the standard way of cooling a system has always been for the CPU fan to blow the air onto the CPU heat sink, which is incorrect.

I cannot in all honestly believe that someone that claims they have years of experience at building PC systems would make such an erroneuos statement.

So then which is it? Am I a liar or are you seriously mistaken about PC cooling?

...and again, even if the PSUs from the PC/XT/AT era had a fan, doesn't mean it was responsible for cooling the entire system since day one, unless the designer made it so, but not all systems were designed to use the PSU's fan for cooling.

No, only those that met the standard.

Since when do the vast majority of systems have the CPU fan blow onto the heat sink? Again, this is not the way the "majority" of systems are built. Blowing the air onto the CPU is a relatively new thing and far from a "standard" method of cooling a system.

Do you honestly believe that? Seriously?

Yes, seriously.

*rendered speechless*

Evidenced by dust getting clogged in the CPU's heatsink fins. If the air was being blown, the dust would settle elsewhere in the system, and the dust would never get a chance to lodge and settle directly beneath the fan.

God i hope you're joking.
The reason it ends up on top of the heat sink is because it's been blown there. If it were being drawn through the heatsink it would lodge on the bottom of the heatsink.

Also evidenced by feeling the air being blown onto the back of one's hand when placed near a CPU fan, and this air can be felt for quite a distance too.

Sure, as it blows up from hitting the motherboard after passing through the heatsink on it's way down to the motherboard.

Mounting a fan to draw air through such a heatsink is a great way to overheat the CPU.

Funny, it seems to work for millions of other PCs around the world. That would be why heatsink fins are not closed around the fan, it allows the fan to draw in the surrounding air from the chipset, blow it up to the exhaust fan that expels it out the back of the case.

If you honestly believe this then there is no way i can take your statement that the system was working correctly as fact.
As i pointed out in the previous post the fan must blow air through the heatsink to be effective. Drawing it though isn't effective. Due to it's height from the motherboard it would provide next to no cooling at all- remember the pedestal fan?

Agreed on the standard system and non-overclocking. Wrong on the exhaust fan not doing most of the work pulling the hot air out of a system.

I can only go by the systems i've come accross.
Other than custom systems, the PSU moves most of the sir, not the rear case fan.

If you have no alternative suggestions after being supplied the data, then it stands to reason that my conclusion must be correct.

Just because someone doesn't have an alternative suggestion doesn't make the current one correct.

It does until a better theory comes along, and I'm still waiting.

Considering your statements regarding the direction the air flows from a normal CPU fan, i can't take as valid your assertion the system was working as it should.
So your theory for the system failure is even less likely than before.

So then which is it? Am I a liar or are you seriously mistaken about PC cooling?

Or the 3rd option- you are seriously mistaken in your beliefs & your knowledge of CPU cooling is flawed. As it appears to be in relation the PSU providing the system cooling for a couple of decades.
I have no doubts about my knowledge, empirical or otherwise.

I suppose I could make the same argument, but in reverse. Where is this getting us again?

Nowhere.
That you honestly believe the standard method for cooling a CPU is to draw air through the heatsink just makes me realise this this discussion has been pointless- you believe what you beleive regardless of the facts.

I have 40 computer systems in my house right now. I could check each and every one of them for you. A portion of them are AT designs too. They all have the CPU fan pulling the air off the CPU heatsink, not blowing. Every one of them.

Only if you fitted the fan that way, or the people that worked on the systems after they left the factory did so.
Seriously.

In this case, blowing the air onto the CPU caused the failures that required components to be replaced.

Once again, claiming that the method that cools 100's of thousands of PC systems is something i can't accept.
Why it should work for all of them, and not that one just doesn't add up.

Because it doesn't work for 100's of thousands of other PCs. I'm sorry that you're mistaken on this, but this fundamental fact is obviously where the breakdown is happening.

Yep- this is definately the breakdown point.
It does work, continues to work, yet you refuse or are unable to acknowledge it.


EDIT- fixed typos & formatting.

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Grant
Darwin NT

In this case, blowing the air onto the CPU caused the failures that required components to be replaced.

Once again, claiming that the method that cools 100's of thousands of PC systems is something i can't accept.
Why it should work for all of them, and not that one just doesn't add up.

Because it doesn't work for 100's of thousands of other PCs. I'm sorry that you're mistaken on this, but this fundamental fact is obviously where the breakdown is happening.

Yep- this is definately the breakdown point.
It does work, continues to work, yet you refuse or are unable to acknowledge it.

I dont have enough knowledge about thermal designs or air flow mechanincs to say if the CPU fan blowing onto the mobo is better or worse, but the specification from Intel about this is pretty clear:

"An active CPU fan heatsink with airflow directed towards the main board is assumed in the TAC 2.0 Design Guide and is needed to properly cool the processor and surrounding components." (Intel Thermal Advantaged Chassis design guide).

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I have an idea, both of you go out and build two identical computers. One with the fan blowing and the other sucking. Set them up on SETI and come back in a couple of years when one or the other burns up. If you both have the same results then you will know almost for certain which is the best way.

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PROUD MEMBER OF Team Starfire World BOINC

I have an idea, both of you go out and build two identical computers. One with the fan blowing and the other sucking. Set them up on SETI and come back in a couple of years when one or the other burns up. If you both have the same results then you will know almost for certain which is the best way.

I like that idea. Don't think it will be a couple of years for one of them though.
Any bets?

Regards,

A

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i like that ideal....they can suck and blow, see who comes first.....

Get over it.....the computer died..... new subject

Bedtime-read-and-a-half this one...

i like that ideal....they can suck and blow, see who comes first.....

Get over it.....the computer died..... new subject

Yes Please.

Regards,

A

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i like that ideal....they can suck and blow, see who comes first.....

Get over it.....the computer died..... new subject

Yes Please.

Regards,

A

Motion carried and seconded, motion approved. Next case.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

You don't have to read a thread if you don't want to. And what was being discussed was relevant to the thread, so this was the appropriate place for it.
Just take a few deep breaths, then settle down petals, and try out another thread that doesn't tax you so much.

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Grant
Darwin NT

So then which is it? Am I a liar or are you seriously mistaken about PC cooling?

3rd option, your're mistaken.

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Grant
Darwin NT