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G4 cooling worth a thought in the PC world as well?

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Allan Nielsen

Senior Member
Joined
Dec 18, 2000
Location
Denmark, Europe
I was at work today, and in a break I suddenly felt the need to take the G4 I was using apart. This is very easy to do, just pull the handle, and it opens to the side. Nice and easy, wish it was like that with my Aopen case as well.

Anyway, I checked out the CPU cooling, and guess what? There was no fan attached directly to the heat sink! There was this BIG motherf***** aluminium-looking heat sink sitting on the CPU, and it didn't even feel hot or anything. Lots of fins, and the base was like many times the size of the G4 core. It had the size of 1.5 slot1 coolers! (Or maybe my eyes were playing tricks on me)

Then I noticed that there was a big, silent fan inside the case blowing air on the cooler, from about 5-7 cm extra distance than normal. What do you all think of this? Is it something worth a shot some day, or should we just continue using those relatively small fans attached directly on top of the heat sink?

Anyway, I just thought that it looked way different than I am used to with PCs, and I wondered if anyone in here had ever given it a try on a pc, and checked for temperatures.
 
W

William

Guest
it is also important to remember that the G4 uses a different architecture than the P3 or Athlon as it is a RISC chip vs. a CISC chip. They work like this. A CISC chip will have a routine in it that will say walk across the room and step over the box in the middle of the room. The RISC chip in contrast will have several routines like Walk, Walk, Step over, Walk Walk. The result is that the RISC chip produces far less heat. The theory behind RISC is that you can only fit so many transistors onto a chip and that you will eventually run out of space. That has come no where near to happening as IBM has invented a way to stack the transistors vertically and somebody, I think IBM too, invented a three atom transistor. SO the RISC theory does not need to be applied to the PCs yet, maybe fifteen years from now. Athlons and P3s and durons and celeys really need fans and heatsinks to run at decent temps.
 

dimmreaper

Senior Member
Joined
Dec 16, 2000
Location
home
RISC CPUs do not run cooler because there RISC CPUs. RISC CPUs just tend to have less transistors because much of the tasks a CPU has to deal with is worked out in software at compile time. For example, I'm pretty sure RISC CPUs don't have a branch prediction unit, as branch prediction is carried out at compile time.

It's also important to note that the G4's RISC CPUs do no run nearly as fast as our CISC CPUs. If you put a heatsink that large on a celeron 600 you could passively cool it as well.

Apple is actually very smart on this issue:

Open the hood on a Sun Workstation and look for a fan on the CPU heatsink. You won't find one.
Look at some pics of $1000 OpenGL graphics cards used for CAD, look for the heatsink. You won't see a fan on that heatsink either. Go look at a Matrox G450, look at the heatsink, no fan again.

Were seeing a pattern aren't we. So what do all these products have in common? They are all "professional" computing products. Basically businesses will upgrade less often, but they aren't afraid to dish out the cash now to ensure they get the most out of these systems. Since they upgrade less often, a fan may have a chance to fail sometime during the products useful-life-span. It all comes down to reliability! If a system goes down, It may cause thousands of dollars of lost time.

I don't know if G4s are overclockable. But I imagine that with the addition of a huge fan you could really do some overclocking with them(I bet you could do 1GHz).

I've long loved MAC hardware, but it is cursed with an inferior operating system , and a lack of applications. From what I have heard from developers, it takes 2-3 times longer to write a MAC application. I've also heard from a few Linux developers that Linux is cheaper and easier to develop for than M$ OSes. Once Linux becomes more main stream, I think many developers will embrace it.
 

rugby

King of Cats Senior
Joined
Feb 2, 2001
Location
Chicago, IL
Well, I have a 1ghz Duron and a 400mhz G4 sitting right next to each other and can definitely give some input. I won't get into the windows vs. MacOS debate at all because I really like them both, and having used Win2k and OS X for a while now they both show some good thinking at times.

As far as distributed.net client benchmarking goes the G4/400 tests at about 3.4mkey/sec while the Duron/1ghz tests at about 3.55mkeys/sec. This is with the latest versions and the velocity engine enabled G4. I like the distributed.net client because is really taxes the cpu and is cross-platform. SETI is cross platform but is not compiled for the velocity engine of the G4 so is really hampered by this.

Cooling:
DIfference of night and day. My Duron box is HOT compared to the G4. My G4 case has one silent fan in it that really is mucho efficient at cooling the case. I can have the case open and touch the heatsink while running d.net client and not melt my fingerprints off. My Duron has 4 fans including the heatsink and PS, and I am scared to come anywhere near the chip. Also, the fans are kinda loud (although that really doesn't bother me) and when I have my Duron fired up the room definitely gets warmer. I prefer having the windows open when benchmarking due to heat in the room.

Overclocking:
This has to be a joke. My little 50 bucks Duron 650 hits 1055mhz stably. I think the 2 systems are relatively similar in speed/ram/hard drive/ and the DUron system was a lot cheaper. Overclocking involved a pencil and then finally a defogger kit and a tweak of the bios on my Kt7-RAID board. Overclocking a G4? Fahgedaboudit. Unless you feel comfortable soldering resistors and all this other crap then don't bother. ALso, if you own an early G4 they had massive problems getting over 500mhz so even if it was easy, it wouldn't work.

I hope this post is helpful.
 

dimmreaper

Senior Member
Joined
Dec 16, 2000
Location
home
rugby-

If I had a MAC I would be very comfortable soldering on it. Do you know of any MAC overclocking guides any were? It would make some interesting reading.

Allan-

Just read that AMD doc some more. Found out why some SocketA MoBos have the 4 heatsink holes and some don't. The Athlon specs call for the holes, but the Duron specs don't. I'm going to go check the AMD recomended motherboard list. I'll bet the KT7 is not Athlon reccomended because of it's lacking of the 4 holes. I'll let you know what I find :)
 

dimmreaper

Senior Member
Joined
Dec 16, 2000
Location
home
Well the KT7 is on the Athlon list. I bet some money had to change hands for that to happen :)
 
V

Van

Guest
Jeff: I don' think that a very large overclock would be possible with a G4, almost certainly not to 1 Ghz. The reason apple clock speeds are so low is that they're been having horrible yields speed wise when manufacturing the chips. I've seen a couple articles about how even 600 mhz chips are extremely rare. And since overclocking is basicly making a slightly flawed chip run at that particular chips maximum potential speed, overclocks above 600 are very unlikely.

That sound about right?
 

dimmreaper

Senior Member
Joined
Dec 16, 2000
Location
home
Van (Mar 13, 2001 11:58 p.m.):
Jeff: I don' think that a very large overclock would be possible with a G4, almost certainly not to 1 Ghz. The reason apple clock speeds are so low is that they're been having horrible yields speed wise when manufacturing the chips. I've seen a couple articles about how even 600 mhz chips are extremely rare. And since overclocking is basicly making a slightly flawed chip run at that particular chips maximum potential speed, overclocks above 600 are very unlikely.

That sound about right?
Yields of higher than 600 with passive cooling and "acceptable" voltages are low. Once you throw on a fan, and jack up the voltage to beyond normal levels, I bet you could OC it to fairly high speeds.

AMD is not selling CPUs above 1200MHz because they assume a worst case scenario for cooling when they test the chips. But you throw an Alpha on some of these chips, and you see them hitting 1.4GHz

Apple (Motorola makes them I believe) is not selling CPUs above whatever they are selling because they assume passive Apple cooling will be used when they test the chips. But throw a fan on the heatsink, and your talking a whole new ball game now. Maybe 1GHz was a bit over the top, but 800MHz is very much possible.
 
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William

Guest
my friend has a G4 and wants to overclock. He said there are like two or three resistors that have to be soldered on I believe. But yes, I do think the G-4 would be highly overclocklable, and the G4 is darn fast(mostly due to the high optimization macs have over windows) but you could yield some nice results. On the speed issue, if you believed apple you would accept the gigaglop result they got. Actually, the benchmark the used was quite old although they have since toned that slogan when the US said they couldn't sell supercomputers outside the US. I personally found that to be quite amusing. I think the best speed comparison I heard was that a G-4 500 was ROUGHLY equivelent to the P3 750-800. This would support all the Mac people who said it was the fastest computer at the time, and is probably accurate, but of course, why would anyone buy a mac. You have to be able to play Counter-Strike at least two hours a day to remain sane.
 

rugby

King of Cats Senior
Joined
Feb 2, 2001
Location
Chicago, IL
Jeff-

http://www.xlr8yourmac.com is a great site for Mac stuff in general. They have links to lots of overclocking info. The forums there are great also, however they're down for maintenance or an upgrade to the server.

As far as the "why buy a mac" comment that was really uncalled for. If you think macs are for sissies or whatever please check on OS X and tell me the mach kernel isn't manly enough for you.

Games? I don't play games on either computer except for a little 4x4 evolution on my G4. It was a christmas present and it's a fun game.
 
OP
Allan Nielsen

Allan Nielsen

Senior Member
Joined
Dec 18, 2000
Location
Denmark, Europe
dunno260 (Mar 14, 2001 12:55 a.m.):
...but of course, why would anyone buy a mac. You have to be able to play Counter-Strike at least two hours a day to remain sane.

People doing Desk Top Publishing don't care much about CS when working, and for that the Mac is a great tool. I use a G4 at work for HTML editing, and I like it! So there are lots of reasons to buy a Mac... just think about all the cool colors they come in! :)