Why is overclocking the cpu the big thing....

[Shockwave]

Why do people seem to prefer to overclock the cpu? Wouldnt you get a much more noticable improvement by overclocking your bus speed as opposed to the cpu speed?

 

[Bartman39]

Uh dude when you overclock your buss speed you do overclock your cpu... Intel cpu`s are multiplyer locked so that is the only way to do it... Also AMD`s dont seem to like high buss speeds more than likey because there buss is doubled (in effect...) anyhow (I think I`m saying this part right???)

 

[Vegito]

It's cheaper, if you overclock a 550E to a 733E and run benchmarks, it's the same as buying a 733E but you only paid the price of 550E... part mail fail but you probably replace the cpu by then..

AMD doesn't like overclocking ? I seen so many people with durons from 600 to 1Ghz+ but you're right, amd's ev6 doesn't like too much change.....

 

[kranky]

Overclocking CPUs is easier and more reliable than overclocking the bus. Many peripherals won't work on an overclocked bus, and disk drives may become corrupt or fail altogether.

 

[pdo]

I get a bunch of CRC errors when downloading files if I overlock FSB to something like 110MHz. So I had to back mind down to 100MHz and up to multiplier.

 

[Lord Evermore]

Bus speed overclockability is dependent on many variables. Your PCI cards have to be able to handle an increased bus speed, so does your memory, so do your IDE controller , chipset and hard drives and CDROMs.

Increasing the speed of the CPU only depends on the CPU being able to handle the increased speed, which almost all newly purchased CPU's can do because both AMD and Intel have very good quality control as well as very good fabbing methods these days. They're producing a lot of chips which they COULD mark as much higher speeds, but they have to supply a certain number of the lower speed chips to meet the demand. So what could have been a 900MHz CPU gets marked as a 600MHz (after testing that it CAN do 600MHz) and they don't bother to check whether it will go higher. So you buy it for the price of 600MHz and find out that it CAN do 900MHz, and you get a free 300MHz.

Overclocking the bus does provide a lot of performance gain, which is why people were doing it before Intel multiplier locked their CPU's. Now that they can't just change the multiplier, it's the ONLY way to overclock an Intel. (Athlon/Duron/TBird require some work to do it, but you can still change the multiplier on them.)

Overall, the CPU speed is far more likely to be overclockable by a wide margin than the bus speed is going to be able to. You might have an Intel CPU capable of being overclocked by 300MHz, but the FSB on your motherboard may only be able to go up to 112 or something due to a picky IDE controller or hard drive, or your AGP card may not like the non-spec AGP speed. With a marked-as 550 PIII (100MHz bus), that's only a 66MHz increase in speed for the CPU. So you're pretty much stuck with that.

If you've got an unlocked CPU, like a modified Duron, you could increase the bus speed to 112 AND increase the multiplier, giving you even more performance increase.

 

[PliotronX]

When you say "overclocking the CPU", do you mean increasing the multiplier? Overclocking the FSB is essentially overclocking the CPU as well, and also other components in the system. Bartman is right, 7th generation AMD processors don't like high FSB frequencies, while they handle high multipliers just fine, and they are able to be increased, unlike Intel's counterparts, which are multiplier locked.

 

[Vegito]

You can't overclock the multiplier on a intel cpu but you can't really overclock the fsb on AMD, only a little..

Sooooooooo Intel CPU - change FSB only so you'll need that 1/4 divider for above 112.. for AMD, you run into problem around 104-110 so you change the multiplier...

Overclock either one gives you more speed...

 

[Shockwave]

Sorry, shoulda been more specific...By changing the multipler, you only change cpu speed. but, knowing that the biggest bottleneck of systems is bus speed, why not just oc the bus (which does the cpu as well) and call it could? Does oc'ing the bus & the cpu give a noticable performance gain over just oc'ing the bus?

 

[Dark4ng3l]

of corse the cpu is faster so you will se an improvement. What do you think is faster a t-bird 750 ir 1.1 gig?

 

[AMDfreak]

Shockwave,

Whenever you are able to do both FSB and multiplier OC'ing, the results are generally better than with just using one of the methods by itself. However, because Intel CPU's are multiplier locked the only option is FSB tweaking. Luckily for intel owners, the GTL+ bus on the newer BX and i8xx chipsets has been very receptive to high FSB speeds. As for AMD owners, we can adjust the multiplier, but due to limitations in the EV6 bus and KT133 chipset, FSB tweaking is very difficult. The EV6 bus is a Double Data Rate bus, so if I were to bump my FSB from 100 to 110, in reality it's like going from 200 to 220. In this case, FSB tweaking can be very unstable with very little adjustment, so most AMD owners just choose to stick with multiplier tweaking only. I have heard that the KT133 is actually governed, much like a car's engine can be, so that we are unable to reach speeds that the next chipset will offer. Whether or not the upcoming AMD 760 and VIA KX266 chipsets will allow better FSB tweaking remains to be seen, but I'm sure Anand will have the skinny for us.