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Overclocking

Discussion in 'Mac' started by BaleFire, Aug 18, 2001.

  1. BaleFire

    BaleFire MSC Footman

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    This may be a stupid question but how do you overclock a computer and what does it do. I get that it will give ya more mhz (that sounds wierd but ya get the idea) is there some drawback (there must be otherwise theyed come already Oc'd right?) Thx
     
  2. Haite

    Haite Forum Moderator

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    Overclocking is the process of speeding up the clock that controls the internal speed. On Macs it's done a variety of ways, for instance on the new G4's there are four tiny jumpers on the processor card that control speed, you have to either solder or cut those jumpers in certain combinations to control the speed. The downside of overclocking, is that since you're forcing a processor to go faster then it's rated speed, it gets hotter. The heat increase can be managed with larger heat sinks and more powerful fans, although if the core temperature gets too hot the silicon can literally melt (this is bad :nod: ). The method of overclocking is often system specific, so if you want any further information on your set-up, we'd need specs. I'd highly recommend looking into some large tech sites (like xlr8yourmac.com) for more information. You can really wreck your entire system if you're not careful.

    --Haite
     
  3. Jakeman

    Jakeman MSC Founder and Donator

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    ah yes, the dark art. heat is the main concern. if you overclock too much though then the main concern will prolly be stability.

    i remember on the old g3s (like cow's) they all had a wonderful little jumper block that makes for easy ocing. wa happen? :(
     
  4. Wulf

    Wulf MSC Knight and Donator

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    heh I still have one... but I tried to OC to 450 Mhz from 400 :( and it locks up after like 30min-1hr after bootup... I guess I could solve that by not using Seti, but... waaaaaH I wanna :p .. any ideas that don't involve buying stuff from the store (I'm going to college soon and my parents don't want me out of the house till I pack...)
     
  5. cowofwar

    cowofwar Peasant

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    Ok, thing about overclocking is, yes, to answer your question all computers are overclocked to begin with. Say Apple is selling 867 chips, so motorola will manufacture potential 867 wafers en masse. Now some of those chips wont be able to do 867, some will be able to and others will be able to go higher. So if a chip can't hit 867 motorola will clock it down to 800 and see if it's stable, if it is, then they'll sell it. Otherwise it gets trashed (733 isn't the same chip as the 800 and 867).

    Because the chips must have a bit of overhead to sell at those speeds, you have a chance of overclocking a bit past the default speed but you're approaching the boundary of stability. Some chips are sold so close to their limit that you can't overclock them at all without crashing. This is normally at the beginning of a certain chip's lifetime. When the producer of the chip adds more features or revamp the chip it can go higher than what they might sell it at since they're not selling a faster chip computer or they don't have enough returns on the high speed to sell a faster version. If you're lucky to get one of these monsters you can overclock it by almost 25%. Take the 1ghz G4 for example.

    If you have a G4 you may be out of luck, G4s are infamous for having small overhead and low returns on overclocking. There are also jumpers on the actual mobo that you'll have to make and break connections with. If you do this you'll need a chart explaining which jumpers to use. I'd also suggest conductive paint instead of soldering.

    Now G3s, mmmm... They not only had more return in the overclocking arena (Probably due to the fact that IBM makes them and they can't sell G3s faster than the current G4s. IBM has better technology so they're selling the chips at a slower speed than their max capability.), but they're much easier to overclock. Instead of a couple jumpers on the mobo, there is a jumper block. It's the little yellow rectangle by the processor. If you want to overclock it, get the chart explaining which jumpers do what and then go ahead. Pull off the jumper block and inside you'll find pins. Move the pins to the corresponding location of your desired speed and put the jumper block back on.

    Nowadays, there isn't much risk of frying your processor unless you're using a p4 or something. Or if your processor is set to 3x the bus and you decide to up the bus speed and the processor...BAD MISTAKE!
    Say your bus is 100mhz and the processor is 450mhz. That would be a 4.5x multiplier to the bus speed. Now if you up your bus speed to 150mhz your processor automatically jumps higher since the processor speed is decided by the multiplier. Your new processor speed at the new bus speed is now 675Mhz. Now say you were an idiot and thought you'd up the processor to 600mhz from 450mhz and at the same time up the bus from 100mhz to 150mhz. You may just have fried your you upped your multiplier to 6x to obtain 600mhz and then by upping the bus to 150mhz your chip is now at *gulp* 900mhz. No chip gives you 200% return.

    When overclocking make sure you monitor the temperature with gaugepro or another heat monitoring utility. Record the temp of your active chip before and after. If it's quite a bit warmer you may want to get additional cooling for your computer. Make sure you find out the highest reliable temperature for that chip at the producer's site.


    And remember, if you **** up your chip. It's not covered by warranty.
     
  6. cowofwar

    cowofwar Peasant

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    If it's crashing then it's a heat related problem. Sounds like you have a G3 B+W. Go to radio shack and buy some thermal paste and if you want to, a 486 fan. Pull off the heatsink and apply the thermal paste onto the cpu. Then put the fan on top of the heatsink. If the heatsink/fan combo is too high you can file down your heatsink.

    I haven't tried the second idea since the thermal paste works well and my g3 is stable and happy at 450@500.

    You could also try removing the internal speaker since you might not use it. This will leave a hole in the front covered by the speaker thingy. Go buy a fan, place it on the inside covering the old speaker hole and put it on suck.
    I've head this works well.

    If your computer doesn't boot up it might also be limitations on the cache and not the cpu. Drop the cache speed with the multiplier on utilities like G3/G4 cache profiler. Mine right now is on 1/2x so my cache is at 250mhz. If it doesn't work drop it to 1/3x so it'd be at 166mhz or something like that.
     
  7. cowofwar

    cowofwar Peasant

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    Blegh, sorry about those long-winded responses.
     
  8. Jakeman

    Jakeman MSC Founder and Donator

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    what cow said
     
  9. Wulf

    Wulf MSC Knight and Donator

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    Cow... you are somewhat correct... G4 400 Pci... used the G3 mobo, but with a new case... :/ gotta love Apples cost cutting procs...
     
  10. cowofwar

    cowofwar Peasant

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    Whoa, where'd you get the G4 case?
     
  11. Wulf

    Wulf MSC Knight and Donator

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    k , lets say that after 40 days of constant use at 400 Mhz, my proc is at 100*F... what is safe for a early G4 chip... (temp wise)
     
  12. cowofwar

    cowofwar Peasant

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    No idea for a G4.

    My G3 is at 500mhz at 93ºF. That's active temperature using a heatsink and no fan.

    Your guess is as good as mine. Run a search on google.com/mac or go to www.xlr8yourmac.com
     
  13. Wulf

    Wulf MSC Knight and Donator

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    OKay, I OC'ed to 450 (448.8 effective) and gauge Pro says all good things... 34*C (down from 38*) and 93*F (96* under load...) hmmm looks good... I am gonna D2, stress test it for a while... bbl with results... btw I did it with some crap radioshlack jumpers, so it looks like carp :p
     
  14. Haite

    Haite Forum Moderator

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    Heh, my G3 runs cooler then that, but it's not OC'd. My athlon, on the other hand, runs at about 114 F average. I've got a fatass fan with heatsink actually on the chip (with thermal compound), that makes a helluva lot of noise. I'm planning on getting a smaller on-chip fan, and then another fan that sucks air in on the front of the case.

    --Haite
     
  15. Wulf

    Wulf MSC Knight and Donator

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    heh I can't hear my comp... and btw updating the temp readout... holding at 100* F... not bad... the last time I did this, it froze every 3 minutes... yay
     
  16. Autolycus

    Autolycus Forum Moderator

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    cool shit, my 533s run at 71*F with IE and a few other puny apps open, and 78-85*F with diablo 2 running
     
  17. Jakeman

    Jakeman MSC Founder and Donator

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    guage pro's temp reading is always wrong on my g4 400. don't know why.
     
  18. powerhouse

    powerhouse Peasant

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    It's pretty hard to toast a cpu. If you have a good hsf, and dont raise the voltage, you're safe 99.99% of the time.
     
  19. Jakeman

    Jakeman MSC Founder and Donator

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    just don't do like a customer did today at my work.

    he came in saying his computer was freezing shorting after POSTing. we popped open the case, checked the fans, etc. it turns out he had installed a new heatsink but he put it on backwards so the lip on the bottom of the heatsink was on the wrong side. this made it so the heatsink wasn't even touching the processor part, it was like 1mm above it. haha! (overheating being the issue) :D
     
  20. cowofwar

    cowofwar Peasant

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    ahahhaahhahah

    What a retard!
     

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