AMD's SB750: Enabling Higher Phenom Overclocks?

by Gary Key on 7/23/2008 12:00 AM EST


Back to Article

  • bbqchickenrobot - Monday, August 11, 2008 - link

    This article claims the PCIe slots are 1.x when they are in fact 2.0 as stated in the manual, website and other sources.

    Just wanted to make everyone aware of this. There are four total PCIe 2.0 that can run 2x PCIe 2.0 cards at x16/x16 or 4x PCIe 2.0 cards at x8/x8/x8/x8

    To get around this, get an X2 version of the Radeon HD 3870 or 4870 and then crossfire with another one or drop down to a standard 3870/4870
  • MikeODanyurs - Wednesday, August 06, 2008 - link

    Anyone see AMD OverDrive 2.1.2 available for download yet? It's Wednesday the 6th, official release day of 790GX+SB750. Reply
  • CZroe - Monday, July 28, 2008 - link

    "it's unclear whether or not whatever AMD is doing here can even work on K8 if they tried."
    Nope. I've been waiting for a board/BIOS maker to expose this chipset setting since the Athlon XP Mobile Barton CPUs first made me aware of it. My Mobile Barton Athlon XP was basically a completely unlocked bin-sorted Athlon XP 3200+ that was stable at lower voltages expected to be run at much-lower voltages and clock speeds.

    With it, I discovered that there was clearly a chipset setting not exposed when my Mobile Barton failed to reach 200/400FSB in an nForce2 Ultra400 board (the Shuttle board inside my SN45G XPC... the FN45-whatever IIRC) while the same CPU could easily do 450+FSB in an Asus A7N8X-E Deluxe and an Abit NF7-S. The solution? Drop a thin wire inside the socket to make this completely unlocked CPU *DEFAULT* to 400FSB and it runs perfectly fine and can even go higher (the L12 trick/mod).

    With the default FSB being the only difference (all settings/frequencies, including the FSB, were the same), it was very clear that it was related to a calibration setting that was automatically applied by the chipset based on the default FSB (100MHZ/200FSB for this unlocked CPU). Previously, I could only get to 333FSB before Memtest 86+ would start giving errors. There were some reports of even the overclocking boards (mentioned earlier) getting higher with the L12 trick and later many had BIOS updates and board revisions that seemingly integrated the trick. Regardless, the setting was still not exposed and was likely not even something the board/BIOS makers could expose (though they could spoof the default FSB I'd assume). It looks like AMD, having full control of chipset and board-level options here, has finally let the cat out of the bag.

    Although the FSB has become the HT bus, the behavior is the same. Changing the calibration setting allows for higher clocks while actually becoming unstable at lower clocks. Ever accidentally erased the OSCAL calibration value on a PIC microcontroller and had to find a working value through trial and error? I'm guessing that this is why it was automatic before.
  • initialised - Sunday, July 27, 2008 - link

    Leads me to suspect that ACC is a means of adjusting the substrate potential to provide a bias to the bottom of the SOI stack to control the threshold voltage of the transistors. Reply
  • SirYes - Friday, July 25, 2008 - link

    To spread the word:

    | To be honest I find it hard to believe that they have a campaign
    | against Linux. There would be nothing to gain and would have
    | a zero fiscal gain.
    | I think it is a bug you have found

    After looking through the disassembled BIOS for the last several hours, rebooting it, and tweaking it more, I'd say this is very intentional, I've found redundant checks to make sure it's really running on Windows, regardless what the OS tells it it is, and then of course fatal errors that will kernel panic FreeBSD or Linux, scattered all over the place, even in the table path for Windows 9x, NT, 2000, XP, and Vista, and had to correct them (Well, at least divert them off into a segment of RAM I hope to god I'm sure about)

    No, this looks extremely calculated, it's like they knew someone would probably go tearing it apart eventually and so tried to scatter landmines out so as to where you'd probably hit one eventually.

    So if it is a mistake, or incompetence, then it's the most meticulous, targeted, and dare I say, anal retentive incompetence I've seen.
  • Will14 - Friday, July 25, 2008 - link

    I've never had much faith in Windows OC tools.
    However if this one actually works and AMD can up their speeds a little then I may switch back for my next system.

    I must say my 6400-8400(cheated got an e3110 with 20% discount when first released and they were all $280 or OOS for $170). Upgrade path was seamless and I feel bad going from 1950Pro to 8800GT 512 but I follow my wallet not the company I root for.

    A cheap system built off cheap Black Box edition(OC'd easily with their tool) and 4870x2 would be pretty sweet come this December if the new cores are kicking and the utils work(a lot of ifs). Not that I need a new system though, but if one did. I don't see nehalems being affordable anytime soon(unless new AMD core rocks(another if)), although my mobo would support. I like the $200 mark for processors $100 for HDD's $200 for gpu's plus generally only needing 1-4 new parts for a yearly $400ish upgrade which is cheaper and allows better performance than the $1-2k some people build.
  • Zisyncmon - Friday, July 25, 2008 - link

    Does anyone know when they will release more info? Gary? Any estimates of when to expect another article? Or will we have to be in suspense all weekend. Reply
  • geok1ng - Thursday, July 24, 2008 - link

    I am really hoping that AMD can make some competition on CPU market as they did on the IGP (man i am really looking forward to the next IGP offer from AMD, the 780G is the king, the next chip will be a market consolidating move for sure)and VGA markets but i am not joking when i ask:

    Will a 3.1Ghz ultraoverclocked quad core Phenom beat a $80 E2180@3,1Ghz in gaming and common day tasks?

    As i remember the C2Ds are 15%-25% faster clock per clock, and the AMD CPUs consume MORE power for the same tasks , because they take LONGER to do the same task of a C2D.
  • jslusser - Thursday, July 24, 2008 - link

    So does this ACC on the SB750 do anything for vanilla Phenom's? Will it unlock the multiplier on the non-black Phenoms or just make them more stable with the HT and memory over clocks?

    I'd like to see where the 9150e/9350e can get to with ACC and the power usage, since the voltage, etc doesn't change. So many questions...
  • HazaroudsSmoker - Friday, July 25, 2008 - link

    First, you can't unlock the multiplier on the non Black Edition Phenoms. They are locked at the factory during manufacturing and can not be altered.

    Sounds like there will be an advantage still to having the SB750 with Vanilla Phenoms.

    Can't wait for Benchmarks.
  • steveyballmer - Thursday, July 24, 2008 - link

    Why does this board look so cheap and lego-like?">
  • Maroon - Thursday, July 24, 2008 - link

    "We can't help but wonder if it is because AMD is going a little too far in the sacrifices it's willing to make in the quest for higher clock speeds." Hello? This is the one thing that keeps the latest generation AMD procs from being competitive with Intel's. Are we sacrificing stability that you're not telling us?

    And then the bitching about the integrated LAN...please? Sounds like you guys are just pissed that AMD won't tell you the new SB works.

  • ughtas - Thursday, July 24, 2008 - link

    I remember from months ago, that the L2/L3 cache performance was changed to support larger cache sizes. Is it possible that the tweaks that ACC makes to the processor timing improve the cycle time or allow better lookahead? Reply
  • nubie - Thursday, July 24, 2008 - link

    I for one am glad to see an AMD processor at 3.4ghz, if this is a new trend I am all for it.

    I want to know what kind of clock-for-clock performance this has compared to an Intel, just for kicks.

    I had a chat with a knowledgable IT guy, he claims that Intel systems boot faster to a usable desktop than AMD, and he has side by side bench tested them.

    I didn't think to ask if he had done tests with comparable level 2 cache, an area that I think may be causing problems, AMD has no processors with 1M level 2 cache except a few older 90nm cores. They are just giving up in this area to Intel.

    I applaud them for making neat server processors, but 512k level 2 cache is not cutting it these days.

    I have been running on a Core2 "solo" Celeron 430 @2.4ghz for the last several months, and I must say while it is pretty damn fast there are times when it seems to "lock" or "micro-freeze" when it is doing a lot of multitasking.
  • Xray1 - Thursday, July 24, 2008 - link

    Na, the L2 cache is pretty unimportant for AMD processors, as the on chip memory controller is very fast. For example, the difference between 1M L2 and 512k L2 K8 processors at otherwise same speed is for most apps somewhere in the range of 0-5%.

    Your single core Celeron locks in multitasking, because its single core.....single core is completely obsolete these days.

    As to the boot speed: This heavily depends on the system config, bios etc. Plus: How often do you boot? I do that once a day and don't really care if it takes 30 sek more or less.
  • Xray1 - Thursday, July 24, 2008 - link

    One reason for the proprietary 6pin connection between SB and CPU could be: It's simply a hardware dongle to ensure the best possible oc results can only be found on AMD chipset mainboards......It is very hard to believe AMD could not have made the same thing possible by MSR programming in the CPU.
    If AMD does not get more specific on this, we need true hardware nerds to sniff on these 6 lines and try to reverse engineer what's happening on them.
  • pmonti80 - Thursday, July 24, 2008 - link

    Not so fast my friend.
    Just look here:">
    Now we have a more plausible explanation that does not involve strange "black magic".
    ACC is just another form of CPU skew.
    No big deal for anyone, end of the story.
  • ZootyGray - Friday, July 25, 2008 - link

    Your linked source is not saying what you are saying. It's a guess. and conclusions are stated as being based on the assumption that the guesses and assumtions are true.

    Your attitude overrides that - NOT END OF STORY. And the results reported here stand untouched by your opinion based on what someone else said is assumption and guess. (right or wrong).

    Additionally the author of your referenced article is very gracious in excusing himself if his guesses and assumptions are incorrect. And yet he ungraciously comes down pretty heavy in ending his article. And that is what has triggered your own feigned knowledgeable statement.

    Maybe it is true - and maybe not. But oclokrs must live in perpetual embarrassment if it is true - and you embarrass yourself in the face of hard testing and accurate reporting of results of that testing. If I wanted speculative guessing and assumption and self agrandisement based on possibly erroneous opinion, I would go read bullshit at toms bubblegum guide. You might enjoy that more since you are apparently so inclined.

    You put 60 hours work behind your statement and you might understand a cheap slap.
  • pmonti80 - Friday, July 25, 2008 - link

    You are right on my attitude about last post. Sorry about that.
    But still I think the analysis of what could be happening here (based on both articles) is probably more in the line of CPU skew or some similar thing. It seems way easier to do with just 6 pins (4 or 5 really usable for ACC).
  • ZootyGray - Friday, July 25, 2008 - link

    I agree with you. And it seems plausible (at least) that skew is quite probably it. The report however is about facts and not /guess /assumption /opinion - and therein is it's value.

    I fully expect that some will hack into this secret - much like was done before with AMD cpu's when they used the graphite pencil trix - it was all great.

    Perhaps I owe an apology to you. I am a little overzealous since I have been seeking a factual, scientific review/testing site for some time. I like what's happening here. I hope I did not come down too heavily on you and the useful info that you presented. (altho the 'embarrass' part in that info,is merely abuse and useless shaming - essentially the stuff of flamewar, ego and fear (which reflects on the author).

    Your point is taken and thank you for your (this) reply.
  • Xray1 - Friday, July 25, 2008 - link

    The possibility that it is all about cpu skew/timings does not contradict what I have said. Why do you need a 6 pin connection from a southbridge to the CPU to change these settings? You can do that with simple register programming (MSRs). That's just like what has been done in the past (especially in timing settings of the AthlonXP FSB).

    So for me the big secret 6pin connection still looks like a big hardware dongle to allow for AMDs overclocking tool to only work on AMD chipset mainboards. They wanted to make it 100% non-software accessible, so there would be no way of doing it on non-AMD chipset boards. That's all I said. And yes, it's also speculation. But as long as they keep it cloed source, it's a non-accessible feature for other chipset makers.
  • ZootyGray - Friday, July 25, 2008 - link

    @ xray

    Agree. However we don't know. Are they going to keep it secret? Is it about competition? or proprietary? Is there more to it? Is there a hidden ?thing? in Phenom? Is there "black magic"? Has it all been a deliberate lag behind so that they can come roaring back to life and look like the greatest thing since the resurrection? Look what they did to nvidiot with the 48x0 release. And the new CEO wants to offer more performance. Lots going on here = wow! This has my attention, and I want facts.

    My point is that Anandtech is already barking up this same tree - they don't know - they have inquired - and they are reporting known facts - and that is the real food that we have come to eat. More will be revealed. Maybe the answer is the "don't dare mention"; but I doubt that. Maybe a lot of things. It's all exciting to me as AMD makes some noise.

    I watch and wait.
  • eetnoyer - Thursday, July 24, 2008 - link

    "error of margin"?

    I think you meant confirmation, not conformation.
  • The Preacher - Thursday, July 24, 2008 - link

    The clock speed reported by CPU need not tell the whole story. The new system might actually drop a clock cycle here and there and might not increase the CPU performance at all, despite the higher reported frequency. Reply
  • CyberHawk - Thursday, July 24, 2008 - link

    What is the product that we dare not mention its name? Mentioned twice in the article.

    If there is word about Overdrive Utility I guess that it is a new CPU on horizon.

    What do you think?
  • nubie - Thursday, July 24, 2008 - link

    I don't think it is a new CPU, in "Final words" they seem to hint it is a new IGP with a lot more performance on tap.

    If they can storm the market with a 4850 for $200, I am sure that they can integrate something to run today's games at minimum settings on the motherboard and keep it under that price.
  • luk1999 - Thursday, July 24, 2008 - link

    Could you test overclocking on this motherboard with some standard (non-Black Edition) Phenom? Reply
  • dvijaydev46 - Thursday, July 24, 2008 - link

    I wish you did at least a few benchmarks and published. I was very curious to see how a phenom performs at 3.5 GHz. Reply
  • MikeODanyurs - Thursday, July 24, 2008 - link

    My SB (supposedly SB700) has the same production week and only 2 digits and one letter difference on my Gigabyte GA-MA78GPM-DS2H motherboard. Anyone know if it's the letter or the 2 digit numbers that identify the SB750?">
  • imaheadcase - Wednesday, July 23, 2008 - link

    Hardly can read pictures.. :P Reply
  • steveyballmer - Wednesday, July 23, 2008 - link

    Looks like a board from Matel!">
  • OrphanShadow - Wednesday, July 23, 2008 - link

    I know the pin link with Phenom chips is what gives them the extra headroom with ACC, but will this also apply to the AM2+ Budapest based Opteron Quads too? Reply
  • helldrell666 - Wednesday, July 23, 2008 - link

    I dont why, but when it comes to AMDs products, i get the worst scores from anandtech reviews.
    Maybe,Charlie demirjian was right after all, anandtech hate AMD.
    I got the worst 4870 results from anandtech.
    At tomshardware and techreport, the 4870 did much better.
    In your previous review,the 9850BE reached 3.3GHz on 1.38v.
    Do you hate AMD anandtech?

  • cdbular - Wednesday, July 23, 2008 - link

    "Do you hate AMD anandtech?"

    No they don't, but Intel maintains this WEB, Just look at the ads in the page...
  • ZootyGray - Thursday, July 24, 2008 - link

    Ads? What ads?
    Dude - you would enjoy FIREFOX w 'Ad Blocker' - there are no ads :)
  • helldrell666 - Wednesday, July 23, 2008 - link

    Im tired of shintel and nshitia. All this propaganda to destroy the image of AMd/ATI.
    But,the time will coe when DAAMIT will rape them all.Its just a matter of time.
  • jdizzle1337 - Wednesday, July 23, 2008 - link

    Too bad AMD hasn't worked itself back to having the credibility to create "rumors".

    Phenom round 1 was 100% hype and obsolete upon release. Sorry AMD you are on believe it when i see it status.
  • wingless - Wednesday, July 23, 2008 - link

    Did you not read the review? The SB750 works as advertised in a big way. Reply
  • Guuts - Thursday, July 24, 2008 - link

    AMD actually advertised something?? :-p Reply
  • Harbmike99 - Wednesday, July 23, 2008 - link

    Yea I know the CPU has a bug. I have never seen it I have the patch turn off. But will this new SB help it too. I have not overclocked it (too much just once to see if I could get 2.5, and I did) because I am stil useing a older AM2 board, and I am planing to buy a new board and give the old board and X2 cpu to a freind.

    So will it help?
    I would love to get to 3 ghz. I have seen some say on fourms they got that. What so you guys think?
  • jay2o01 - Wednesday, July 23, 2008 - link

    Anyone else intersted how a Phenom 9850 performs at 3.0 ghz with a 2.4ghz+ NB? What kind of improvements would this yield over the stock speeds? Reply
  • Zisyncmon - Wednesday, July 23, 2008 - link

    Yeah I'd agree, it will take some benchmarking to really see what improvement this OC'ing does to performance, but I am sure they are busy finding good settings to test at. Reply
  • wingless - Wednesday, July 23, 2008 - link

    "In the end, we know after a good 60 hours of testing, over 600 different settings, 400+ screen shots, and countless reboots that Advanced Clock Calibration works, yet we do not know anymore about ACC at this point from AMD than SpongeBob SquarePants."

    AMD does nothing but right their wrongs these days. The SB750 is gonna be big for them. I'm amazed that Anandtech went through so many combinations trying to bring this thing down. They have proven without a doubt that this technology works.

    I also can't wait until next week. They have given us confirmation that 790GX and 790FX boards with SB750 will be coming out NEXT WEEK! Also they keep mentioning some part that they "dare not mention". WTF is that going to be? I thought 790GX+SB750 was going to be the big news. Theres something else? Next week will be exciting for AMD in all the GOOD ways.
  • ZootyGray - Thursday, July 24, 2008 - link

    Yup - I come here to hear about the results of what I call "brutal testing" rather than read somebody's hype or bias or sloppy inconclusive testing. I am still fairly new here but I believe Anandtech is the real thing.
    I want that to be true, esp. after wasting my time at tom's bubblegum guide with there trash bias garbage misleading bullschtein socalled reviews.
    These guys are working hard to get the real goods - and in contact with AMD, delaying reports promised 'tomorrow' - who cares - they are willing to go to amazing lengths to output accurate info after deeper investigation.
    This is no kiddy's website - it's a hard read to get through it; and I know I am not the only one who will reread it to better comprehend what I missed the first time through. This testing is consistent with the articles on 'the 3 amigos' and the one about the recent additions to the AMD line, including the 9950. Take it apart, what makes it squeal.

    Also, it seems there is something different about the 9950, and it's not just an oclok 9850.

    Looking forward to more next week - and the ?? mystery ?? item????
    Big change on the AMD scene - wow.
  • Calin - Thursday, July 24, 2008 - link

    I've quit reading Tom's Hardware long time ago - when I think it was a good site. However, Anandtech was better overall, and one site was enough :)
    As for in depth reviews... this should qualify as an easy reading, look for the technology behind NVidia's 280 and 260 series GPU for a "transistor-oriented" article - that's a hard read indeed
  • Comdrpopnfresh - Wednesday, July 23, 2008 - link

    I am really interested to see how an ASUS or DFI board with the new sb do in overclocking and performance. As mentioned this board is more of a feature-rich pick. And just looking at the charts of ACC off on the foxconn vs the ASUS with sb600, I hope there will be more of an improvement with a fresh sb750 variant.

    Interesting though about the pci-e 1.1 and lan choices by amd. Is it possible having those two remedied would hinder the improvement by ACC?
    Really looking forward to new comparisons to Intel chips with the new change. Hopefully with 45nm parts and ACC, amd can have a good go.

    One thing I would like to know though: What are the specs on the sb750 foxconn vs the asus sb600 in terms of the number of phases in power delivery?
  • Goty - Wednesday, July 23, 2008 - link

    I think that there must be some underlying issue with either the chipset drivers or windows itself when it comes to differing final overclocks, as the CPU shouldn't necessarily be aware of what kind of software its running, other than the fact that a few more registers are being used. IS there any evidence that this is a Phenom-specific issue, or might it affect Athlon64's as well? Reply
  • Locutus465 - Thursday, July 24, 2008 - link

    Quite honestly, either way I would run 64bit over 32bit any day of the week period... I'm sorry but the little bit of extra performance you get OCing really doesn't out weigh the many many advantages 64b vista has over the 32b variant (and over XP). Simply put, 32bit operating systems are all but done in my home... I do run 32bit vista on my laptop but only for the following reasons:

    HP put 32bit on here, and it seems to me all their custom drivers and software (which seem to be required to keep the system from crashing) are all 32bit... so oh well.

    This is a budget laptop to begin with and it maxes out at 2GB RAM... The extra overhead of 64b would just be more of a performance killer than anything else.

    No gaming will be done on this laptop (so no need to worry about future games needing more that 2GB for a process) and I have my desktop at home if I need to manipulate large flat files.

    Now my desktop? Yeah...
    Phenom 9850BE
    4GB OCz DDR2
    Radeon 3870...

    It's getting the 64bit treatment all the way :)
  • CyberHawk - Wednesday, July 23, 2008 - link

    ... boy, I was waiting for this one :D Reply
  • FireTech - Wednesday, July 23, 2008 - link

    So was I ;)
    It leaves me with more questions than answers though. Time to re-read and await further developements/articles.

Log in

Don't have an account? Sign up now