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#21
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What's the point of overclocking?
"mike3" wrote in message ups.com...
So then why do they sell them as X speed, anyway, if they are "exactly" the same? But if they are no different, why do they sell them as such? As I see, you are not getting correct answers so far. The thing is that all processors are different, every individual processor, even if it is made on the same wafer. The reason is in inherent statistical variations in transistor quality across the wafer, and across every chip. The variations are due to subtle differences in mask alignment during multi-phase exposures, due to kinetics of etching and film depositions (especially if some layers like gate insulation are only several atoms thick), and god knows due to what else. As result, every block in a CPU performs differently, some slower, some faster. To achieve reliability in computations, processors are tested at extreme specified conditions - lowest voltage and highest specified case temperature, when all transistors perform slower. The tests also cover extreme data switching conditions, since there is some internal crosstalk between signals that depends on data content and sequences. Also, there are certain industry-acceptable margins (10-15%) above the guaranteed conditions. If a CPU fails that suite of tests at certain frequency at that margin, it gets binned down to a lower frequency, etc. So, as you can see, every CPU should be overclockable by 10-15% simply by definition (of course, that margin definition strongly depends on manufacturer's financial circumstances and the level of competition :-) Then, an overclocker usually uses extensive cooling to keep Tcase way below the temperature at which the particular CPU was tested. It gives an additional (I would say 20-30%) margin in clock rate. Or, when using extreme water or liquid gas cooling, the margins are way better. This kind of chip use does not do any electrical harm to the processor, except that there might be mechanical fatigue problems due to extensive thermal cycling. More, overclockers usually try to rise supply voltages. Elevated voltages lead to faster switching gates, and it gives additional speed margin. However, elevated voltages may cause rapid deterioration of the chip, and may cause gate oxide breakdown and other slower effects from increased electromigration effects in metal interconnects. As result, the chip might simply stop functioning one day, or certain inner block will produce a subtle error during calculations you never tried. Again, there are built-in margins into max Vcc based on certain life expectancy of a processor, so a slight elevation should be tolerable. However, effects of voltage are typically exponential, so the safe overvoltage margins are much lower. In short, the point of overclocking is to narrow operating conditions of a CPU and hope to maintain those conditions all the time. If a substantial voltage increase is involved, then it is no different from gambling with limited information and elevated risk. I hope this answers your question. Cheers, - aap |
#22
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What's the point of overclocking?
Alexi Tekhasski wrote: "mike3" wrote in message ups.com... So then why do they sell them as X speed, anyway, if they are "exactly" the same? But if they are no different, why do they sell them as such? As I see, you are not getting correct answers so far. The thing is that all processors are different, every individual processor, even if it is made on the same wafer. The reason is in inherent statistical variations in transistor quality across the wafer, and across every chip. The variations are due to subtle differences in mask alignment during multi-phase exposures, due to kinetics of etching and film depositions (especially if some layers like gate insulation are only several atoms thick), and god knows due to what else. As result, every block in a CPU performs differently, some slower, some faster. To achieve reliability in computations, processors are tested at extreme specified conditions - lowest voltage and highest specified case temperature, when all transistors perform slower. The tests also cover extreme data switching conditions, since there is some internal crosstalk between signals that depends on data content and sequences. Also, there are certain industry-acceptable margins (10-15%) above the guaranteed conditions. If a CPU fails that suite of tests at certain frequency at that margin, it gets binned down to a lower frequency, etc. So, as you can see, every CPU should be overclockable by 10-15% simply by definition (of course, that margin definition strongly depends on manufacturer's financial circumstances and the level of competition :-) Then, an overclocker usually uses extensive cooling to keep Tcase way below the temperature at which the particular CPU was tested. It gives an additional (I would say 20-30%) margin in clock rate. Or, when using extreme water or liquid gas cooling, the margins are way better. This kind of chip use does not do any electrical harm to the processor, except that there might be mechanical fatigue problems due to extensive thermal cycling. More, overclockers usually try to rise supply voltages. Elevated voltages lead to faster switching gates, and it gives additional speed margin. However, elevated voltages may cause rapid deterioration of the chip, and may cause gate oxide breakdown and other slower effects from increased electromigration effects in metal interconnects. As result, the chip might simply stop functioning one day, or certain inner block will produce a subtle error during calculations you never tried. Again, there are built-in margins into max Vcc based on certain life expectancy of a processor, so a slight elevation should be tolerable. However, effects of voltage are typically exponential, so the safe overvoltage margins are much lower. In short, the point of overclocking is to narrow operating conditions of a CPU and hope to maintain those conditions all the time. If a substantial voltage increase is involved, then it is no different from gambling with limited information and elevated risk. I hope this answers your question. Cheers, - aap So are you saying then, that overclocking chips by a little bit (say 7%) is not as big a risk as I think? And is there really a vast conspiracy to delude people into thinking that some chips are built to run faster than others? I'm still curious about the life expectancy, as even if the overclock suceeds without a hitch, it's the long term effect that could come back and bite. Would the 7% vanity overclock significantly reduce the lifespan of the processor? I'm using the 7% figure because it's in the "safe" margin you give and because it probably wouldn't give any useful gains, ie. just to get an idea of what is going on. If you overclock, say, a 3 GHz chip by 7% so it's running at 3.21 GHz, is that really a good speed increase? Can you really notice it? Ie. is it really WORTH it in the first place?? |
#23
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What's the point of overclocking?
"mike3" wrote in message ps.com... If you overclock, say, a 3 GHz chip by 7% so it's running at 3.21 GHz, is that really a good speed increase? Can you really notice it? Ie. is it really WORTH it in the first place?? Put it this way...it's worth it enough for some people to pay a few hundred pounds more for the official chip that clocks at that speed! JW |
#24
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What's the point of overclocking?
"John Whitworth" wrote in message ... "Ed Light" wrote in message ... "Ed Medlin" wrote With today's systems, you can adjust the processor frequencies without raising anything else that would cause any major issues. Don't forget the memory and the bus, such as hypertransport, go up with the clock, and you can't raise the cpu multipliers on most cpus. If you have value memory you'd hit a wall just a little way up if you didn't change the ratios. But only if your motherboard didn't allow the FSB and memory clock to be adjusted independently. I can raise my CPU FSB and memory FSB completely independently. JW That is the idea I was trying to get across.....maybe just not too well.....:-) My present board is the same. I have to run my memory a bit lower because at the time it was the fastest I could get my hands on, but now things are a bit faster. |
#25
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What's the point of overclocking?
"Ed Light" wrote in message ... "John Whitworth" wrote in message ... "Ed Light" wrote in message ... "Ed Medlin" wrote With today's systems, you can adjust the processor frequencies without raising anything else that would cause any major issues. Don't forget the memory and the bus, such as hypertransport, go up with the clock, and you can't raise the cpu multipliers on most cpus. If you have value memory you'd hit a wall just a little way up if you didn't change the ratios. But only if your motherboard didn't allow the FSB and memory clock to be adjusted independently. I can raise my CPU FSB and memory FSB completely independently. Wow, that's neat. I think it's pretty rare. Most boards change the memory ratio in relation to the fsb. So, to raise the fsb, you'd set the memory as a slower type. -- Ed Light My present board will allow me to set my memory bus slower as I raise the processor frequency too. I think I have 3 choices that are dependent on the processor speed or can be manually set. One of them always seem to be pretty close to the stock speed, one higher and another lower. These ratios change as I change the processor speed. I have 533mhz Samsung DDR2 that runs just fine without any errors up to the 660-670 range for sure. I have never pushed it further because my processor just won't go any more anyway. I plan on a Core 2 Duo build soon and will have a go. It is an EM64T Prescott I-630 (3.0ghz) that runs at I-660 (3.6ghz) speeds. The I-660 was about double the price of my processor a couple of years ago. Yea, it runs hot, but it runs the hot at stock too. The same die is used on all of this series. My temps are exactly the same at 3.6 as they are at 3.0. No increase in core voltage is needed. Ed Ed |
#26
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What's the point of overclocking?
Well, I don't want to do it, sorry. It obviously is risky, since you're
pushing the thing over it's designed speed, but I suppose though that if done right the overclock could work, however I'm not that big a gambler! The more you overclock, the higher the risk. I don't think a few "vanity" hertz would do much anyway ("vanity" level = "safe" level.). Not enough to be *really* useful, and any more would be pushing the envelope too much. I doubt that pushing it up from the speed I've got now (2.8 GHz) to 3.0 GHz (+200 MHz), what I call a "vanity" increase, would really do much, and anything more just doesn't feel safe to me. Like one said, it's best not to get greedy, and any "non-greedy" overclock does not seem like it would be worth all the fuss! If I want to play around with overclocking things, I'd better go and build myself a system that I wouldn't really care about if I lost it, ie. a pure "experiment bed". Remember, it takes only ONE mistake to nuke the chip, and if you don't watch the temp like a hawk... It is a hobby really. With today's processors they have so much protection from overheating that you really have to try hard to damage a processor. A few years ago, AMD chips did not have thermal protection and would fry once in awhile, but since then all processors have some sort of thermal protection. Intels throttle back their speed and eventually will just shut themselves down if temps get in the danger zone. 2.8-3.0ghz is not a major overclock and should be fine and you should not have to mess with any core voltage increases that can cause more heat. Whether you will notice the difference or not is debatable. Ed |
#27
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What's the point of overclocking?
"mike3" wrote Well, I don't want to do it, sorry. It obviously is risky, since you're pushing the thing over it's designed speed Have you been reading the responses? The chips are identical except that some need a tiny bit of extra volts to go top speed. But -- I agree that you shouldn't overclock. Those who are leery can't dig it. Also, if you have a car without the mods to the engine of a higher model, you should never add those mods. It wasn't designed for it, and might blow. If you have a toothbrush that comes without attachments that a higher model with the same base comes with, you shouldn't add the attachments. ;-) If a small appliance comes with a power brick of a certain spec., you should never use an off-brand of the same spec. Etc. etc. Sorry! Couldn't help it! :-) -- Ed Light Bring the Troops Home: http://bringthemhomenow.org http://antiwar.com Send spam to the FTC at Thanks, robots. |
#28
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What's the point of overclocking?
"mike3" wrote If you overclock, say, a 3 GHz chip by 7% so it's running at 3.21 GHz, is that really a good speed increase? Can you really notice it? Ie. is it really WORTH it in the first place?? Only in certain cicumstances. Let's say you're time-shifting tv and it tops out your processor and drops frames and is a little jumpy. Now let's say a small overclock is enough to cure it. Or, to make enough room to do some other work while time-shifting in a small window. Or you are rendering a movie, which loads up the cpu 100%. Whatever overclock you do shortens the rendering time by that much. If it was taking 5 hours, then a modest overclock could take almost an hour off. In my case, my 20% overclock often means my train simulator gets just out of the intolerably jumpy zone. From 14.5 to 18 fps, when in a highly detailed area. But if you are just going to surf the internet and do word processing, then overclocking is not necessary. A Duron 700 will do the trick. Assuming that all chips can only overclock a little before going crucial is not correct, though. 50% overclocks are common, with the chip still running cool with stock cooling. Try to remember that it is the same chip as the fast one, but requiring a small voltage increase. It is not getting near a destructive temperature, and it has passed a long torture test. Example: Sempron 64 2800+ overclocked from 1.6 to 2.4 with an increase of .05v. Never goes over 45C. 60C is the maximum specified for those chips, from what I know. The chip was about $60 with heatsink. Now, is that not attractive? If not, I see you are overpowered by your safety precaution instincts. But trying to convert us is pretty pointless, don't you think? We've had lots of good overclocking experiences, of course going through some trepidations to get there. Maybe you're hoping we'll convert you? It seems strange -- sorry. -- Ed Light Bring the Troops Home: http://bringthemhomenow.org http://antiwar.com Send spam to the FTC at Thanks, robots. |
#29
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What's the point of overclocking?
"Ed Medlin" wrote My present board will allow me to set my memory bus slower as I raise the processor frequency too. I'm not very expert at the underlying hardware operations; I've thought of that as changing the ratio between the bus and the memory. Oh wait -- for AMD 64, the memory operates right off the chip. Well, anyway. -- Ed Light Bring the Troops Home: http://bringthemhomenow.org http://antiwar.com Send spam to the FTC at Thanks, robots. |
#30
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What's the point of overclocking?
"Ed Medlin" wrote It is a hobby really. With today's processors they have so much protection from overheating that you really have to try hard to damage a processor. A few years ago, AMD chips did not have thermal protection and would fry once in awhile, but since then all processors have some sort of thermal protection. For AMD it's on the motherboard and at least on some can be enabled/disabled, with the crucial temp and/or a speed reductionpossibly adjustable. Mine slows the chip down. -- Ed Light Bring the Troops Home: http://bringthemhomenow.org http://antiwar.com Send spam to the FTC at Thanks, robots. |
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