BIOS Settings

Once everything is working properly and you're sure that the PC doesn't have any problems, it's time to approach the actual process of overclocking. You might want to give the PC a few days of heavy use (system burn-in) just to be sure that it's stable. All of the FutureMark benchmarking utilities are a good start for stress testing a system, and if you buy the registered versions, you can set them to loop continually - at least, the 3DMark versions can be looped; a quick batch file will get the PCMark applications to loop as well. If you can loop 3DMark03/05 and PCMark04/05 for several days, you can be relatively sure that the computer is running stable. We'll use that same approach later to stress test our overclocked configurations.

Here's where things get more complex, and virtually every motherboard BIOS is going to be at least slightly different from what we present here. If you have a socket 939 motherboard, you'll need to refer to its manual (or figure out where the settings are on your own), but most of the names and/or values will be similar to what DFI uses. The key areas that will need adjustment for overclocking are the CPU bus speed, CPU multiplier, HyperTransport (HT) multiplier, memory speed, memory timings, and voltages for RAM, CPU, chipset, etc. Let's cover each of these quickly to explain the process. We'll include BIOS images from our particular motherboard, so you can look for the matching setting in whatever board you're using.


Click to enlarge.

Ignoring RAM for the moment, the way you overclock on Athlon 64 processor is simple enough. The normal clock speed is achieved by running a 200 MHz CPU bus frequency with the maximum CPU multiplier. Our 3200+ Venice has a 10X multiplier, so 10 X 200MHz = 2000MHz. If we increase the CPU bus to 270MHz and leave the multiplier at 10X, we'll have a 2700MHz CPU (provided that we can actually get that to run stably). Because Athlon 64 chips are all unlocked downwards on the multiplier, other combinations of CPU bus speed and multiplier are possible. 10x240, 9x267, and 8x300 will all run the CPU at around 2400MHz, resulting in similar performance. Note that we say "similar" but not "identical" performance: the RAM and other areas of the system will not be running at the same speed, so depending on how the other aspects influence performance, there could be a slight to moderate difference in overall performance.

The CPU bus speed is also referred to by other names. The DFI board labels it "CPU Frequency", while you may find HyperTransport Frequency in many BIOSes. (Some people will also call it the "Front Side Bus speed", which is not technically correct.) CPU Frequency, CPU Bus, HT Bus, etc. all mean the same thing, as the CPU communicates over an HT bus. Along with the CPU multiplier, there is also a HT multiplier (also called LDT - Lightning Data Transport - multiplier in some BIOSes). Most socket 939 motherboards support a 1000MHz HT speed, which is a 5X HT multiplier with a 200MHz base clock. The HyperTransport bus is sensitive to overclocking, so we need to keep its total speed in check. You may be able to run the HT bus at over 1000 MHz, but depending on motherboard and cooling, you will begin to have problems beyond a certain point. We'll keep our HT bus speed at or below 1050MHz by adjusting the HT multiplier as we increase the CPU bus speed (and we may at times drop lower if that brings stability). We can use the 4X multiplier with up to a 260MHz bus, and 3X will get us up to a 350MHz CPU bus (which is more than what most people are likely to reach, and more than what we'll test in this particular article). It is also possible to adjust the width of the HT bus from 16-bits up and down to 8-bits, but rarely does that help stabilize an overclock, so we'll leave it at 16/16.

We've covered the CPU and HT speed adjustments, but there's more to it than simply picking a target clock speed. In order to reach a stable overclock, you will often need additional voltage to the CPU and chipset - which affects the CPU speed and HT bus speed respectively. The default voltage of our Venice chip is 1.300V, but we will definitely increase the voltage as we go beyond a 10% overclock. Extreme overclocking (with liquid Nitrogen or phase change cooling) might go so far as to double the CPU voltages, but on air cooling that would be disastrous (not to mention few if any motherboards would even support that in the first place). We'll report the voltages required for each setting later on, but there are really two voltages: what we set in the BIOS, and what we actually get from the system. They may or may not be the same.

Something else that you should disable while in the BIOS is the Cool 'n Quiet feature of the Athlon 64. As that alters CPU voltage and multipliers dynamically in response to demand, it doesn't usually agree with overclocking. We also disable video and BIOS caching, as those are more relics of the DOS era than useful features (as far as we're aware). If you're interested in seeing the default settings that we used on the remaining BIOS screens, we have all the BIOS screens available for download in a Zip file.

System Assembly RAM BIOS Settings
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  • edlight - Tuesday, January 3, 2006 - link

    I've found a way to overclock and retain the Power Now/Cool'n'Quiet.

    I let the motherboard do it's Cool'n'Quiet thing but I don't load the AMD driver. I run CrystalCPUID, which lets me set up the multiplier and voltage of each of the 3 cpu steps.

    The voltage setting of the motherboard, for my Gigabyte, has to be on Auto for Crystal to be able to change it.

    The highest Crystal can go with my 1.4v 3000+ Winnie is 1.45v.

    This let me take it up to 3800+ -- a speed of 2.4. 240 x 10.

    So it's running at 1.2 -- 240 x 5 -- most of the time. I set it at 1.2v there and froze it there and p95'd it overnight, as I did to the other 2 speeds.

    For me this is a great compromise between running "cool 'n quiet" and high performance.

    It's only a small percentage speed jump to 2.6, but requires alot of voltage and heat.

    I can't say what the maximum voltage would be for a Venice. Crystal lets me choose higher voltages than 1.45, but it doesn't actually set them.
  • RaulAssis - Wednesday, December 21, 2005 - link

    Some people reported that the Cool 'n' Quiet feature could work in a OC system. Maybe not all bioses support correct scaling of voltages when the system is OC and the Cool 'n' Quiet feature is turned on.
  • JarredWalton - Wednesday, December 21, 2005 - link

    With any moderate OC, CnQ is going to cause problems. It dynamically adjusts multipliers and voltages... something that will usually screw up an overclocked system. I would strongly discourage trying to use CnQ with an OC'ed setup. Some motherboard BIOSes actually disable CnQ automatically if you enable overclocking features.
  • mrmoti - Wednesday, November 30, 2005 - link

    If I understand correctly:

    Performance RAM running at DDR400 2-2-2-8 and Value RAM running at DDR400 2.5-3-3-8

    At same OC on the processor, Performance RAM outperformed the Value RAM by 5% to 10%, being the price something between 80% to 100% more.

    So, what's the impact of runnig faster memory at high lateny? Say DDR500 at 3-4-4-8

    Because looking at the table of estimated latencies, (Performance) DDR400 2-2-2-5 has an estimated latency of 46.5, where (Value) DDR400 2.5-3-3-7 has an estimated latency of 49.75, an improve of 6.5% being in the range of 5% to 10% better.

    By the same table, DDR500 3-4-4-8 has an estimated latency of 42.4, an improvement of 8.8% over the Performance DDR400 and 14.7% over the Value DDR400, based only in latencies.

    Can anybody run a benchmark confirming/denying this?

    Being the case that the price of DDR500 with those timings is in the middle between Performance and Value RAM
  • T Rush - Sunday, October 16, 2005 - link

    One of the main focuses of this article seems to be value -vs- performance RAMs when over clocking, but you chose to run the performance RAM at settings where is doesn't perform, shame on you Jarred Walton, very disappointed

    If you look at the settings you used to test the two RAMs at...
    http://images.anandtech.com/reviews/cpu/amd/athlon...">http://images.anandtech.com/reviews/cpu...niceover...
    ...you see that the MAX speed you where able to run the OCZ Rev2 at was not in it's "performance envelope", as the OCZ Rev2 is one of the worst performers in this speed range http://www.anandtech.com/memory/showdoc.aspx?i=256...">http://www.anandtech.com/memory/showdoc.aspx?i=256... <OCZ Rev2 at 266MHz, and all the other "performance RAMs" beat it

    But if you look at how the OCX Rev2 does work at much higher speeds, where it does perform...
    http://www.anandtech.com/memory/showdoc.aspx?i=256...">http://www.anandtech.com/memory/showdoc.aspx?i=256...
    ...you find that it is performing much differently than what you tested at, and would have shown a much larger performance lead over the value RAM

    How did you get this on to Anandtech? How could you show such a bad comparison of value -vs- performance RAM on a site which has always shown so much information about how these RAMs perform?

    I not only blame you, but also the editors for not catching how badly you have managed to make performance RAM look. It is clear you were trying to prove that cheap RAM can falsely perform as well as high-end performance RAMs. If you truly wanted to show what performance RAM can do when over clocking you either needed to run the OCZ Rev2 at much faster speeds, or use a different performance RAM that works well at the sub 270MHz speeds you tested at.
  • JarredWalton - Sunday, October 16, 2005 - link

    This is one set of RAM run through extensive tests on one platform. I've seen the same RAM run faster in some other systems, but not a whole lot. Just because some DIMMs reach DDR636 doesn't mean that all of them do. I could run this RAM at 3-4-4-8-2T timings at DDR600, but it actually ran worse than 2.5-3-3-8-1T with the lower memory ratio.

    What is clear is that I wasn't trying to "prove" anything. I was running some comparison tests with a system using two different types of RAM, and I'm sorry that you don't like the results. What I did prove was that someone one a budget could build a very fast system. An FX or San Diego core with higher quality RAM and a better motherboard would be better overall, but price/performance it would get stomped by this <$1000 setup.
  • T Rush - Monday, October 17, 2005 - link

    I don't find the OCZ Rev2 to be a good example of the high performance RAM everyone thinks it is, as it doesn’t perform well at the speeds you (and most everyone else) use…not compared to other good over clocking RAMs
    Granted some of the other performance RAMs do cost much more than the value RAMs, and even more than the OCZ Rev2, but they would have shown a greater performance difference than the value RAM which in your tests was not able to run any faster than its stock rated speeds or timings
    Your testing shows that running RAM at faster speeds adds very little performance over stock speed value RAM, and that is because the timings/speed relationships of that peculiar performance RAM at those peculiar higher speeds were not good.
    As I said before, all the other performance RAMs beat it, and perform much better at speeds under 270MHz than the OCZ Rev2 does

    Using the right RAM at the right speeds to run the best timings is the true art to over clocking, as RAM timings and speeds can allow the AMD64 to perform at much higher levels when over clocked

    I do not disagree with your results, as that is how those RAMs perform:
    Value RAM only being able to run its rated speeds and timings, not being able to over clock at all.
    OCZ Rev2 running at higher speeds but with such bad timings that it shows very little performance gains unless you are able to run it at CAS 2.5 in the 300MHz range

    I am not a fan of the OCZ Rev2 because of this, but I am a fan of performance RAM over value RAM, even on a budget system.

    If you read clue22’s reply “so basically what the everybody is saying about the value RAM vs. low latency more expensive RAM is that for the athlon 64 it is basically a waste of money (i.e. you only get about 5% performance gain), but usually spend 100% or more money to get the "better" RAM.”
    …and cyptonomicon’s “and its nice to see those ram comparisons. good to see those results on the latest a64 platform and confirm once again that the ram makes only a few percentage points difference”
    …next intellon’s “I understand how/why the memory quality is not too imoprtant (5-9% increase for 100 bucks = not worthy)”

    Clearly by using the OCZ Rev2 you did not show what spending a little bit more for better performing RAM can do. You have shown that running RAM at speeds with timings where it doesn’t perform well is a waste of money, but this does not answer any questions about value -vs- performance RAM
  • JarredWalton - Monday, October 17, 2005 - link

    I've got X2 benchmarks with four different types of RAM in the works:

    OCZ VX
    OCZ Plat Rev2 (TCCD)
    Mushkin Value
    PDP 2x1GB 2-3-2-5-1T

    Other than the fact that 2GB of RAM helps out certain tasks (BF2 load times!), the total performance difference with those configurations is still not huge. With a 3.5V RAM voltage, the VX would do better, but even then the difference isn't above 10%.
  • T Rush - Thursday, October 20, 2005 - link

    for a budget system I would say the socket 754 is better...as the motherboards and CPUs are cheaper...and you can get ClawHammer CPUs with the larger performance 1MB L2 cache
    the only thing you miss out on with the 754 is the dual channel memory mode(which only adds very little performance anyway)...but by over clocking the core:memory speed you can easily match the performance gained by the greater bandwidth of the dual channel mode (this could be why the socket 939 doesn't show large gains from overclocking with the memory 'in-sync'..as it can't use all the bandwidth the faster memory gives)

    with a mid-range system you could pick a 10X multi 3200+ Venice, or even a 11X multi 3500+ Venice(either of those would have a much better CPU multi for overclocking than the 3000+'s 9X multi) which would allow you to keep the HTT/HTL speed at a more reasonable level(270MHz and 245MHz to reach 2.7GHz CPU speed...where a 9X multi CPU would need a 300MHz HTT speed to run the CPU that fast)
    ...but the 3200+ and 3500+ are costing $190 to $250...so for not much more you could have a performance San Diego core on the 939 platform (3700+ 11X multi SD is only $267 now)
    ...so for $80 to $40 more I would go for the larger San Diego core...I would also spend the ~$20 more for CAS 2 RAM (over $90 Value RAM)...thats like just $100...for a computer with much better parts...and say you use this system for 18 months, that works out to less than $6 a month for a using higher quality parts
  • Deathcharge - Saturday, October 15, 2005 - link

    Jarred this was a great article and did come at a great time as i am in the market for buying a bang for the buck system. One thing you didnt mention (although i saw that in the CPU-z screen shots) is the CPU stepping

    http://www.amdcompare.com/us-en/desktop/default.as...">http://www.amdcompare.com/us-en/desktop/default.as...

    the 3200+ venice core comes in 3 different stepping and i belive the one you used in your article is the E3 stepping which is being replaced with the E6 stepping. Any info on how well the new stepping OC? initial reports from around the net indicate that it doesnt OC very well for some reason would love to read your comments on this.

    Do you know if it is possible to OC to 2500 or 2600O with stock HSF as i would really like to save the money spent on the TT-90 and get a 7800GT (as opposed to x800xl). one final thing would OCZ value VX require active cooling?

    thanks and keep up the good work, really enjoyed reading it and would look forward to future articles

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