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Understanding The Lingo

Guide: Overclocking AMD And Intel CPUs On A Budget
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Many new overclockers leave our user forums never to return when they ask "How do I overclock?" and receive “Raise the FSB or HT clock” as an answer. But once you're armed with the lingo, the principles are fairly easy to understand. Let's cover a couple of the basics.

Frequency

A processor is made up of a complicated series of microscopic electronic switches (transistors) on a pulsating power circuit. The number of pulses (power cycles) per second is called the circuit's “frequency.” It takes at least one cycle for the transistor to change state between on (1) or off (0), and the ones and zeros become part of a data stream.

Modern central processors run at thousands of millions (billions) of cycles per second, or gigahertz. This is the same range of frequencies at which microwaves and mobile phones operate, so that a relatively short piece of wire can become a fairly good radio antenna. Preventing cross-communication between circuits, where one circuit acts as a transmitter an the other an unintended receiver, is extremely important.

The conductors on motherboards, called traces, are much longer than those of an integrated circuit, such as a central processor (CPU) or graphics processor (GPU). In order to reduce noise, signal loss and cross-talk, the pathways that connect various processors must run at slower frequencies.

The CPU Multiplier

As the need for increased data speed outstripped the ability of various busses to support it, companies developed a variety of methods to send more than one bit of data per conductor, per cycle. These methods include double data rate used in memory modules, quad data rate used by Intel’s front side bus (FSB), AMD’s HyperTransport (HT) interconnect, and Intel’s recent QuickPath Interconnect (QPI).

Because Intel’s most recent FSB uses quad data rate technology, its clock frequency is a quarter of its data frequency. That is to say, the clock rate of FSB-1333 is 333 MHz (megahertz, or millions of cycles per second). The CPU itself relies on an actual electrical frequency (the clock rate) to set its internal speed, so a CPU multiplier of 10x on an FSB clock rate of 333 MHz (FSB-1333) results in a CPU frequency of 3,333 MHz, or 3.33 GHz.

AMD’s internal HT link uses a 200 MHz clock speed with data rates of five to ten times clock speed, resulting in 1,000 to 2,000 transfers per second. But since HyperTransport supports full bandwidth in both directions at the same time, AMD doubles its name to HT 2,000 (1,000 MHz data rate, 200 MHz clock rate) and HT 4,000 (2,000 MHz data rate, 200 MHz clock rate). The most important thing to remember when overclocking is that both HT 4,000 and HT 2,000 use a clock rate of 200 MHz, so that a CPU multiplier of 10x would provide a CPU clock speed of 2,000 MHz, or 2.0 GHz.

Though we won’t use an Intel QPI-based system today, users should know that it operates in a similar fashion to AMD’s HT link, but at a slower 133 MHz base clock frequency.

Voltage

Frequent overclockers will discuss BIOS settings such as VCore (voltage of the CPU core), VDIMM (memory voltage), and various data pathway/memory controller voltage settings under a variety of different initializations. Some of these will be discussed in detail as we encounter them in BIOS screen shots.

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  • 3 Hide
    tacoslave , July 20, 2009 6:38 AM
    i like these "how to" articles but i still want to see the rest of the twkr article you promised us (quad crossfire 4890's) *sigh* a man can dream can't he?
  • 0 Hide
    snakeeater_za , July 20, 2009 7:20 AM
    Surely people on a budget (like me) would prefer their e5200 to last longer than a 'few months or hopefully a yr to 3?' i know i will upgrade prob in a year or so, so a yr would be fine, but a few months? Pfffft. my proc vid is 1.225 and for 3.33ghz i need a vcore of 1.385 in bios which at idle is 1.36ish. So although im nowhere near 4 at least i wont suffer from electromigration and have to fork out for a new cpu! Just my 2 cents
  • -2 Hide
    snakeeater_za , July 20, 2009 7:22 AM
    Thats obviousl 4ghz not vcore lol
  • 6 Hide
    Crashman , July 20, 2009 7:35 AM
    snakeeater_zaSurely people on a budget (like me) would prefer their e5200 to last longer than a 'few months or hopefully a yr to 3?' i know i will upgrade prob in a year or so, so a yr would be fine, but a few months? Pfffft. my proc vid is 1.225 and for 3.33ghz i need a vcore of 1.385 in bios which at idle is 1.36ish. So although im nowhere near 4 at least i wont suffer from electromigration and have to fork out for a new cpu! Just my 2 cents


    It's all a game of averages. Tom's Hardware hasn't accidently killed a processor by overclocking it in a while, though I'm sure a couple editors have intentionally done so to find the voltage limit. The problem is, once again, you can only look at averages.

    3 months continuous use at 1.45 volts caused an E8500 to lose its OC stability. It had to be clocked down to become stable again, and lost much of its voltage tolerance. It wasn't destroyed however.

    1.40 volts should be significantly safer than 1.45 volts, but until a few people report on how long their cores lasted at 1.40 volts its impossible to tell "how much safer", that is, how much longer it will last. All that's known is that it should last "significantly" longer, but whether that's 4 months (33% longer) or 30 months (10x longer) is the unanswerable question.
  • 0 Hide
    astrodudepsu , July 20, 2009 8:30 AM
    Good show mate.

    I would have liked to see combined charts as a conclusion but that's a minor criticism.

    I'm just wondering what the 'next-gen' E5200 (i.e. the intel people's OC'er) will turn out to be? Some flavor of i5 I assume, but who knows.
  • 0 Hide
    Anonymous , July 20, 2009 9:52 AM
    how is it that im running my q8200 at 3.04ghz stable at 1.25v? weird
  • 6 Hide
    JeanLuc , July 20, 2009 11:43 AM
    Link

    "Intel’s value-priced Core 2 Quad Q8200 uses two of the same processor dice as the Pentium E5200....."

    I don't know why you choose the Q8200 it's a notoriously bad overclocking chip, if you wanted a budget Intel Quad core that had room for overclocking you should have bought the Q6700/Q6600.
  • 0 Hide
    Anonymous , July 20, 2009 12:20 PM
    ”Motherboard MSI P45 Diamond LGA-1366, P45/ICH10R, BIOS 1.5 (10/10/2009)”

    MSI P45 Diamond is not LGA1366, but LGA775. LGA1366 is for Core i7 processors only, LGA1156 is for Core i5 and i7 (only dual channel DDR3-1333/1066). LGA775 is the old socket, for Celeron D, Celeron 4xx, Pentium Dual Core, Pentium 4, Core 2 Duo, Core 2 Quad.
  • 2 Hide
    da bahstid , July 20, 2009 1:05 PM
    No games? Like...none at all? Does anybody even overclock for reasons other than games?

    Otherwise, pretty good article. Though perhaps a better choice for the Intel quad would have been a 9550...I thought they were under $250 by now. Same time, I guess the Q8200 does seem to be a more difficult overclocker...Intel may have intended this to be the case so as not to gut sales of their Q9000 series. And readers may as well know before jumping on a Q8200 thinking it'll overclock like an E5200.
  • 1 Hide
    freak77power , July 20, 2009 1:15 PM
    I agree. Q6700 will reach 3.6Ghz with no problems.
  • 6 Hide
    Anonymous , July 20, 2009 1:24 PM
    It's nice to see a Tom's article that doesn't intentionally low-ball their AMD OC, I'm sick of seeing 3.6ghz PhenomII OCs when we all know they can do better. They could've picked a better Intel quad though, and I think the Intel dual-core OC may be a tad extreme, that's not going to last for daily use at 4.1ghz.

    PS: Synthetic benchmarks should be outlawed until they fairly and accurately give an indication of real-world performance ;) 
  • 5 Hide
    Anonymous , July 20, 2009 1:49 PM
    Awesome12345: What has virtualization to do with overclocking? How many normal users(or even gamers) even use virtualization? Hell, most people probably won't even need it for Windows7 compatibility mode, except for enterprise users. Why not get a 955BE, the 945BE is hardly worth it since it's barely cheaper, why on earth would you recommend the non-BE? That is easily one of the most worthless comments to ever be left for an article...
  • 0 Hide
    awaken688 , July 20, 2009 1:52 PM
    I definitely have to agree with the comments about the poor choice of the 8200. I am one the shoppers this article is referring to and I did not even consider that chip. The Q9550 is $220 right now, so it really is the chip I am looking to purchase. I completely disagree with Awesome12345 though. As an inexperienced OCer, if I am going to go AMD, I am going to get a BE because it offers an easier solution. I also would have like to see a comparison at the end of the 4 chips performance side by side. Not a bad article though minus the worthless test of the Q8200.
  • 0 Hide
    Sihastru , July 20, 2009 2:32 PM
    Q8200 is cheaper, I give you that, but lack of cache, lack of VT, lack of deeper power states... the Q9550 (now only E0 should be on the market) is a far better choice, and it overclocks very well (3.4GHz without any effort at all, 1600 FSB + 800+ DDR2).

    Even so, you must have a dud, since Q8200 should overclock much more then what was achieved for the purpose of the article.

    E5200 is indeed the "new Celeron". A very good cheap chip, if you get it to at least 3.33GHz (1066 FSB + 1066 DDR2). I totally agree with this choice.

    But why did you go with DDR3? It's double the price of DDR2. In real life, if I have to choose between screaming-fast DDR3, or double the amount of that in DDR2... my personal preference is more RAM, even if slower RAM.

    So Q9550 + DDR2 could make the list, at least price-wise. With a little OC, it would be the king of this... let's call it roundup. Some may argue that the 955BE is, but I have my favorites.
  • -1 Hide
    KyleSTL , July 20, 2009 2:47 PM
    Why the exclusion of the Athlon II X2 250? It seems like it would be a perfect candidate for this article. And why did you include the $215 top-of-the-line AMD quad for a 'budget' overclocking article? Wouldn't a Phenom II X4 810 ($140) be a better analogue for the Q8200 ($160)? That way they'd be in the same price class, and they'd both be cut-down quads. Either that or take the 955 against the 9550 ($220), and they'd both be in the same price class and be fully-functioning dies.
  • 0 Hide
    blackened144 , July 20, 2009 2:47 PM
    orangethinkerhow is it that im running my q8200 at 3.04ghz stable at 1.25v? weird

    You got lucky.
  • 0 Hide
    rmc779 , July 20, 2009 3:09 PM
    A very well written guide. Bravo! It would have been interesting from the AMD side of things to test the bus speed overclock versus the multiplier overclock, finding the right balance and achieving a slightly better overclock overall with a mix of the two. I would have also liked to have seen if you had success unlocking the 2 extra cores on the X2 550 with the ACC.
  • 2 Hide
    Shadow703793 , July 20, 2009 3:30 PM
    Acording to Intel data sheets:

    1.45v is the ABSOLUTE MAX voltage for 45nm.
    1.5v is the ABSOLUTE MAX for 65nm

    Absolute Max is defined as "the point where actual damage to the CPU can occur."

    For more info: http://www.overclock.net/intel-cpus/374005-45nm-vcore-discussion.html
  • 0 Hide
    cadder , July 20, 2009 3:33 PM
    I was a budget shopper and I picked the Q9400 when I found it on sale earlier this year at Microcenter. It has proven very willing to overclock. I was thinking about a Q6600 but didn't really want to go that way because of the additional heat output.
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