VERY IMPORTANT! A7M266 Users beware!!!!

The VI/O1 Jumper is default at 2.7V for the DDR memory, however, usually DDR memory is designed for 2.5V. This could cause system instability and cause crashes during heavy memory load. This is especially true when I played 3D games. The fix is to remove the VI/O1 jumper, which set the voltage to 2.5v, I don't understand why Asus doesn't even give the option for 2.5V for the jumper setting, and yet clearly stated DDR RAM uses 2.5V in their OWN MANUAL!

This is documented on the A7M266 review from, which solved the problem I had for 2 months!

Good luck and remove that darn jumper soon!

p.s. I had Crucial 256MB PC-2100 DDR Ram, and on their website it's also recorded 2.5V in specs.
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  1. Coincidentally I am going to buy a A7M266 with Athlon 1GHz(266). I am also buying PC2100 256M kingston ram.
    Thanks for your advice. It will definitely save me some trouble. Thanks pal.
  2. NP, you will love the board. It's a really great board with good overclockability, great performance and stable. One way to get around with messing with the jumpers is to install memory heatsink. My friend did that with the same memory I had (Crucial PC2100 Cas 2.5), and he was able to run it at 2/2/2 at 2.7V stable. But he found it better at 2.5V which allow him to o/c his CPU further without crashing.

    I still don't understand why Asus didn't put 2.5V as an option... odd...
  3. Thanks for the advice, I have just set up the A7M266 for myself seems a great board so far. Do you have a link to the memory heatsink?

    INTELigence is gained by obtaining aMD
  4. #1 Is 2.7V DDR even made?
    #2 How much of a factor is the higher voltage?
  5. standard is 2.5v, 2.7 is overclocked as I understand it.

    Crank it up... way up!! I need that power.
  6. Mushkin memory comes with built on heat spreaders, so I would think this would negate any problems that may arise with the memory. Anyways, how much did your system crash when going 2.7v vs. 2.5v? Was it a big problem, or was it just some minor system instability?

    *EDIT* After going over your listed site, I can see why this is a big deal. THANX A LOAD MAN SERIOUS!!!!

    <P ID="edit"><FONT SIZE=-1><EM>Edited by Boondock_Saint on 08/04/01 05:28 PM.</EM></FONT></P>
  7. 2.5V is standard, I don't think 2.7 are out yet.

    The system runs normally when you do normal tasks such as browsing the internet, use email, etc etc. But as soon as I start to play 3D games, it crashes! So I believe the system hangs due to heavy ram load, and causes overheating. I tried everything to fix this problem including install different drivers, tweaking the video card, formatting, etc. Nothing worked until I forced the VI/O1 jumper to 2.5V. I would have never thought it was a motherboard issue if I didn't read the review from lost circuits.

    Anyway, about the ram heatsink, they are made by thermaltake I believe. So you should be able to find some info from
  8. Good job Frocer.

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  9. Thanks Frocer. I think I'll go ahead with my upgrade to that mobo ..

    You Da Man!

    Yee Freakin' Haw
  10. maybe they made a typo...or..they're just odd...or...

    Comparing AMD and Intel is like comparing a Ferrari to a Model-T…there’s no comparison.
  11. Putting a jumper on the board is no small mistake...

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  12. Excellent hint man,

    I haven't got a A7M266 but instead I have an A7V266. But I recognized your problem since mine also crashes alot with 3D games and immediately looked up my manual. I think the same goes for the A7V266 cause it's also set higher (2.65V) as default. Gonna try it, thanks again...

    Signatures suck :P
  13. Maybe I was posting too quick saying it's the same settings because on the A7V266 the setting applies to not only DRAM, but also chipset, AGP and PCI. So that means the memory can't be set on it's own I guess. This troubles me a bit. Can you, the A7M266 users, aply the settings for only the memory or is it the same as with what I described, having also to set chipset, AGP and PCI?

    Signatures suck :P
  14. The VI/O1 jumper controls the memory voltage exclusively, the VI/O jumper supplies the voltage to the Northbridge, which is chipset, AGP, IDE, etc, and it's set to 3.3V

    They don't have the online manual posted yet for A7V266 so I couldn't look through and help you with your problem, sorry.
  15. Until I read this post I was totally lost on why my Athlon 1.4 was crashing in 3D Mark 2001. I suspected it was the RAM getting too hot, because I couldn't make the system work by changing drivers, and BIOS settings. I never suspected it was the DDR RAM voltage setting on the motherboard. Thanks.

    There is another post on the subject of Athlon 1.4 systems crashing randomly in 3D games, while being fine in general Windows and Internet environments. What is strange though is that the motherboard is question there, was NOT an Asus board. Maybe it is the fault of the AMD 761 reference design rather than Asus. However it would not surprise me that they made a mistake on jumper settings or in the manual. There is already a correction sheet in the manual with regards to incorrect jumper settings being published (regarding the onboard sound and LAN).
  16. I think if you had searched you would have seen it before in this forum. Also lostcircuits mentioned the voltage settings for OC'n Micron DDR chips were different which is similar to your problem (incorrect voltage for the DDR). It is an issue that isn't as commonly known as it should be. That site kicks ass.

    To <b>HELL</b> with your damned cookie.... :mad: ptooo!! :mad:
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  17. oh BTW good job Frocer the if I remeber right the Micron DDR's actually require higher voltage (or much less) I can't remember and on further searching I found that I didn't read it on Lostcircuits, but the site still is really good.

    To <b>HELL</b> with your damned cookie.... :mad: ptooo!! :mad:
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  18. oh and searching again the A7M266 VI/01 problem has not been posted b4... I'll shut up now.

    To <b>HELL</b> with your damned cookie.... :mad: ptooo!! :mad:
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  19. Hehe thanks. To tell you the truth I never thought it was memory problem, I have always thought it was my video card, because the computer only crashes during heavy 3D gaming and such. I use Crucial memory, which is made by Micro, to my surprise I could o/c much better with the default 2.5V, I could go up to 150Mhz FSB stable, when it was 2.7V my comp crashes around 140mhz FSB and I couldn't even do 2-2-2.
  20. Thanks Forcer! I have been through 3 video cards thinking that video was the problem also. I though the jumper-free mode was bullet-proof on the A7M266, but I guess your find killed that theroy. You deserve a trophy. My hat is off to you!

    Fisher of men
  21. I have been running at 2.8 volts for the Crucial, and this is the setting the works the best for me and I am stably OCd to 145FSB from 133. On another forum, i read that a "tech" verified that removing the jumper from VIO1 did not give 2.5, but in fact gave 2.8. I don't know this for a fact, I just pass it along. Also, there have been reports that the VIO jumper settings in the manual are upside down, meaning that the 1-2 and 3-4 settings are inverted. Doesn't that just make your day. In any case, I tried all positions, and the best one (whatever it is) is the position nearest the bottom of the computer. This ran the same as when I removed the jumper completely. I'll search for that Tech post and come back if I find it...

    Here's the quote:

    so basically, if your pc has inadequate cooling, setting vio jumper to 3.45volts may cause your pc to lock-up due to heat. now i've personally have never had this problem but for now, i suggest u set the vio jumper to vio positions 1-2 (default). (but only do this if your're still having problems or want to be on the safe side).

    and also removing the vio1 jumper results in 2.8volts and not 2.5 as previously thought. so now i just use the default settings.
    unless u want to over-clock, i recommend u just leave both jumpers at default. although some have reported that their systems were only stable after removing the vio1 jumper running their pc's at stock speed.

    Can't we all just overclock?
  22. The VI/O jumper is correct, which is default at 3.3V, you can monitor that through BIOS and Asus probe. I can't find a program that actually could monitor the VI/O1 jumper, unfortunately. I know my system became stable after the removal of VI/O1 jumper, all the lock ups are gone. So I guess the best way is to get heatsinks for your ram, so either way you are fine =)

    Another thing, since the 3 settings that Asus allow you to set for VI/O1 are 2.7V(default), 2.8V, and 2.9V. How could you set it to 2.8V by removing the jumper? That's some messed up circuit there..
    <P ID="edit"><FONT SIZE=-1><EM>Edited by Frocer on 08/17/01 11:22 PM.</EM></FONT></P>
  23. Just bumping it back up because there are way too many A7M problems. And I don't wanna link it every time =)
  24. FROCER i have the E776 manual for ASUSa7m Page 20 it states that 2.8v is set with jumpers across pins 3-4.Do you have an older version of m/b or a diff revised manual?Curious as hell to your 2.8v statement.
  25. Yes, same manual same page, 2.7V is default at 1-2, 2.9V at 2-3, and 2.8V at 3-4. None of them are the DDR spec, which is 2.5V, you can even read that on page 25. Please go to and read the review on A7M266. You will see the problem.

    And I don't think I ever told you to set it at 2.8V, I said remove the jumper would set it to 2.5V which meets the DDR spec. The board that lost circuits reviewed was an older version of A7M I belive, that's why their default settings are somewhat different than ours
  26. i wasnt intending to set it at 2.8v overclocked. Just that your previous post was a little confusing thats all.
  27. Thanks for the info Frocer.....I've had the problem for some months now, in fact ever since the board came out, I looked at memory voltages before but due to my ignorance I never thought to check what voltage DDR memory is rated for (Kind of dumb considering the line of work I'm in, I'll leave that up to your imaginations, I'm sure a lot of you are doing similar jobs), I just assumed the lowest setting (2.7 which just happened to be default) would be fine, being nieve I thought to myself why would ASUS's lowest setting be more than DDR memory is rated for.

    Running Generic slop memory wouldn't help the matter either, an increase in voltage is much more than it could handle.

    The problem was confusing however, just like you mentioned...the system runs fine in normal applications such as browsing and everyday windows use.

    The problem manifested itself in 3D games, some games were fine (Max Payne, Undying, Half life), all run fine, but other games such as Operation Flashpoint which constantly redraws the terrain/landscape (generally very memory intensive) would lock the complete system.

    At first I believed it to be a Graphics card problem, unfortunately I had just upgraded all the major components in the system so narrowing the fault down was pretty hard, I ruled the graphics card out after I found that I could run 3D Mark 2001 all night long and not have a problem, I could leave a helicopter in Operation Flashpoint hovering all night long on the maximum graphics settings and it would be fine the next morning, yet fly around the map(again putting strain on the memory) and the system would hang.

    I have removed the jumper and it looks like the problem has been solved.

    Anyway thanks for the tip, chances are it would have been months before I found the answer, in fact I would have probably been on my next motherboard upgrade, a friend of mine spotted your post here (cheers Bleasy).

    Thanks again, it was and still is very much appreciated.
  28. No problem, I am glad I could help. I had the exact same symptoms as you descibed. Some games run fine but some memory intensive games would lock the system. I notice Black & White does it a lot, and Sacrifice as well.

    Hopefully the solution solved your problem. Good luck!
  29. I didnt know you coulds overclock the A7M266 other than the FSB?

    Medication helps :smile:
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  30. With all the respect, I wonder howcome, this is the only one review which deals with this problem.
    How come Asus engineering dept "forgot" about DDR SDRAM specification. And what about Thomas Pabst, how come he didn't deal with this question. Just wonder...

  31. I have the A7M266 (1.4ghz Athlon) mobo with 512MB DDR PC2100 Ram. I go tit from I haven't had a problem.

  32. Well if you read an earlier reply the Mushikin memory actually comes with a built in memory spreader, so that the memory won't overheat as easily compare to other DDR memory.

    About the problem only brought up by lost circuits, I really don't know, I wonder about the samething. Lost circuits is a respected site, so I trust them. Besides it fixes the problem I had so ... =)
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