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  • slewis5150 - Sunday, February 29, 2004 - link

    How is this going to relate to pci eXpress? Reply
  • Pumpkinierre - Thursday, February 19, 2004 - link

    So, Wesley#24, does this mean that some of the low maximum overclocks AT has shown for the A64 might have been as a result of PCI bus failure. Wouldnt it be possible to have a go at 234MHz for the Aopen and some of these other chipsets which supposedly had a PCI lock (nf3,SIS) but may be, like VIA, a dividor transition. Reply
  • Wesley Fink - Wednesday, February 18, 2004 - link

    #23 - As we were testing in the article, none of the current Athlon64 chipsets have working PCI locks - and that includes nVidia and SiS (at least on the ECS). Some of the board makers do have a feature where a 1/7 multiplier kicks in at 233 and the PCI bus drops back to spec. We found that to be the case on the AOpen AK86-L which uses the VIA chipset. Reply
  • Jeff7181 - Wednesday, February 18, 2004 - link

    Ummmm... I was pretty sure Sis and nVidia both had PCI/AGP locks and Via is the only one who can't get it right. Is this untrue? Reply
  • Xentropy - Tuesday, February 17, 2004 - link

    Is this article going to be updated with the new information about 1/7 dividers and which boards have them? Not everyone reads the comments and would see the details. Reply
  • bigtoe33 - Tuesday, February 17, 2004 - link

    Guys I bought the PCI geiger for Wesley from They still show stock but I have just been informed its a discontinued product. If you want one I would grab one now. Reply
  • soki - Tuesday, February 17, 2004 - link

    Good Job Wesley! Reply
  • Pumpkinierre - Monday, February 16, 2004 - link

    Thank you Wesley! Reply
  • Wesley Fink - Monday, February 16, 2004 - link

    As many have suggested as a possibility, it does appear different multipliers kick-in at 234 on the AOpen AK86-L. At a 233 setting PC Geiger shows PCI speed as 38.8, while at 234 the PCI readout drops to 33.2.

  • TrogdorJW - Monday, February 16, 2004 - link

    Is there any chance that a BIOS hack or something could adjust the PCI clock later in the boot process? You stated that you didn't load the OS and only booted into the BIOS. This seems a bit of a quick-and-dirty test, especially with the A-Open having acheived much higher results than other boards.

    My suggestion, in addition to including higher bus speeds, is to also get to the point where the OS is actually being loaded. You don't need to let it boot completely, but at least let it start. Get well beyond the BIOS POST test before assuming that the PCI speed being reported is "final".

    On the other hand, the people questioning whether or not ALC655 and various other devices would run at 43 MHz... that's actually quite possible. Back in the day, I had a Pentium MMX 200 running at 250 on an A-Bit IT5H motherboard, which ended up being an 83 MHz bus and AGP and a 41.5 MHz PCI. (Ahhh... the good old Intel 430 HX chipset. Those were the days! /nostalgia.)

    Later, I had Celeron 300A through 366 all running on 83.3 MHz bus, giving the same overclocked PCI and AGP. Finally, I am STILL running an A-bit BE6-II Rev. 2.0 motherboard on a 133 MHz bus. That motherboard has a 1/4 PCI divider, so PCI is in spec, but the AGP is running 2/3 and is at 88.9 MHz! I have a GeForce 4 MX 440 in it and it serves as my movie/music entertainment center.

    Having been an overclocker since the days of the Pentium 166, I feel quite safe in saying that the "overclockability" of devices varies greatly. Some ATA/IDE setups can't handle more than 5 MHz out of spec (38 MHz or so), while others can clearly handle AGP and/or PCI speeds up to 33% out of spec. Only thorough testing will say for sure what any device can handle, and that's way beyond the ability for any one company/website to test.
  • PrinceGaz - Monday, February 16, 2004 - link

    I'm still awaiting any sort of reponse to the first post in this thread about why no tests seem to have been done at around 233 or 234FSB to see if a 1/7 divider kicks in. Thats the first thing I'd have tried after establishing no PCI lock at say 210 or 220. And yes, you can lower the multiplier on A64 chips so they aren't an issue like I said. Reply
  • Pumpkinierre - Monday, February 16, 2004 - link

    Yes I second ionpro2's #13 suggestion. If you can get higher clockspeed by lowering the multiplier. try your geiger at these higher speeds and see what's going on. Reply
  • Icewind - Monday, February 16, 2004 - link

    Now im curious as well as how you got it that high Reply
  • ionpro2 - Monday, February 16, 2004 - link

    Wesley Fink: No way that the motherboard would've posted with no PCI lock. Think about it: the devices that are dangling off of the PCI bus on the board itself would be running *way* the heck out of specification at the overclocks achieved on the Aopen. Perhaps these have higher tolerences, but I seriously doubt the ALC655 would run at 43Mhz, or the Realtek Gigabit LAN chip, either. Most likely, there are merely windowed dividers for these chips, with a 1/6 and 1/7 ratio. It would make sense for this to kick in at 220Mhz -- otherwise, you are running the PCI out of spec almost 10% down; and I'd be willing to bet whatever optimization is done for aftermarket cards is done for higher PCI/AGP speeds, not lower. *Please* test the AOpen board at 9x240 and see what PCI speed is reported. Reply
  • Wesley Fink - Monday, February 16, 2004 - link

    Pumpkinierre -

    Your question is exactly the reason I stated that I don't know what is happening with AGP on A64 boards. With no PCI cards in my test setup, a working AGP lock could provide quite a bit of OC room. Some sites have reported AGP IS fixed on VIA, but I have no way of testing that. I can tell you for a fact that the PCI slots are not frequency locked on the A64 boards I tested, but the way frequencies are derived in HT it IS possible AGP is locked on some A64 boards.

  • Pumpkinierre - Monday, February 16, 2004 - link

    I dont understand. You got 253MHzx8 and 240x9 on the Aopen A64 mobo when you tested it. That's a lot more than 220MHz. Even if the AGP was asynchronous, which I very much doubt, surely other components on the M'board would have seized?! Reply
  • impar - Monday, February 16, 2004 - link

    I would like to see the same test in nForce2 boards... Reply
  • Icewind - Monday, February 16, 2004 - link

    Sorry, guess I missed the defination of "go pound salt" so i'll take it with a grain of salt. Reply
  • idgaf13 - Monday, February 16, 2004 - link

    If all The motherboard chipset suppliers
    do the same thing ,such as the PCI lock,
    musi be a "deeper"reasoning.
    Certainly if possible ,contractually or technically, they would do it.
    They all need that special selling point ,A point of differintation.

    Basically "go pound salt" ,Icewind.
  • Icewind - Monday, February 16, 2004 - link

    Cause VIA knows better and they still won't comply with the wishes of system builders. For that, I dispute them. Reply
  • gordon151 - Monday, February 16, 2004 - link

    All the chipsets for the A64 don't have PCI locks, why are you singling out VIA Icewind??? Reply
  • Wonga - Monday, February 16, 2004 - link

    I think it is a bit pathetic how none of the chipsets for the Athlon 64 can manage to get a working PCI lock in them.

    Come on SIS/VIA/nVidia, you can do better than that. How they can do it for the Pentium 4 but screw up on the Athlon 64 is pathetic.
  • Icewind - Monday, February 16, 2004 - link

    The first SATA did rely on the PCI bridge but the newer ones have their own dedicated bus to the southbridge so it is not affected by OC. ATA is still attached to the PCI bus if I remember correctly. Reply
  • lebe0024 - Monday, February 16, 2004 - link

    What about harddrive controlers? Does SATA depend on the PCI bus? how about PATA? Reply
  • Icewind - Monday, February 16, 2004 - link

    Cool, no wonder my P4C800-E Deluxe is such a kick ass overclocker. Another reason why not to buy VIA chipset mobo's. Lets hope Nvidia can make a good 939 pin mobo later this year, VIA still leaves a bad taste in my mouth Reply
  • PrinceGaz - Monday, February 16, 2004 - link

    Would it have been possible to raise the FSB to 233 or 234 on those A64 chipsets to see if a 1/7 divider kicks in? I believe the A64 is partially multiplier-unlocked and can have it lowered because of the Cool n Quiet power-saving technology so the CPU itself shouldn't have been a problem.

    If current 8x AGP cards are so sensitive to AGP speed, why not use a slower AGP mode or use an older card which can tolerate a far wider range for some of the tests? I've got an old 2MX somewhere that was quite happy with a 75MHz AGP speed (150FSB on a KT266A chipset, equivalent to 225FSB on current boards) and may well have gone somewhat higher but my PC2100 memory couldn't take any more.

    Interesting article though, surprising about the nForce3 board.

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