IDE driver DMA option

In tweeking my computer settings recently, I ticked off the DMA option in the IDE driver in WIN 98 SE Device Manager. My HD was a Seagate 4.2 Meg UDMA 33. When the system rebooted I got all sorts of errors and it insisted on running scan disk and I got the message "Boot sector record does not agree with backup, do you want to overwrite boot record 1 with the backup" If I answered no, it would repeat the process until I finially answered yes and then, when it rebooted, it couldn't find any windows system files. Booting up in Dos with a floppy and looking at the HD directory, all the folders were empty and ultimately I had to reformat the HD and re-install all my software. Surprisingly the HD now runs much better than before.

Can anyone explain exactly what happened. I won't try it again with this HD but am curious to know when this option can be used correctly?
16 answers Last reply
More about driver option
  1. Not all drives can make use of DMA and can lead to the problems you are describing. If you can use DMA (direct memory address), the drive may run faster--particularly true with DVD drives but maybe for HD.
    It is worth turning on if you can but do not turn it off.

  2. Are you sure you're hard drive and MotherBoard support Ultra DMA 33?
    If not terrible data loss might occur when you vink that box under the windows settings.
    The speed gain is immense, in DMA33 mode you can transfer 33 mb/sec per IDE channel. In not DMA33 mode (thus PIO4)
    you'r maxed to 2 Mb per IDE channel. My Hard disks speed tripled by turning it on.

    You can easely check what speed you're drive is in you're bios. Set the speed option in you're bios to auto. When you see the screen witch reports processor speed, memory, and attached hardwra. Press the pauze button, behind you're hardrive should be it's optimal speed setting.
    PIO 1-4 -> Old slow setting, you cannot use ADM33
    DMA 1 -> DMA33
    DMA 2-4 -> DMA66-100

  3. WRONG:
    DMA1 -> 16MB / sec (but I'm not sure...)
    DMA2 -> 33MB / sec
    DMA4 -> 66MB / sec
    DMA5 -> 100MB/ sec
  4. Well the man said his hard drive was a umda33 drive so then obviously the drives supports it. but does the motherboard or more specifically the controller? What does you bios report the drive as pio mode 4 or umda mode2? If umda mode 2 then it should have worked. Are you curently running it enabled now? A copule of things may have happen and since yu reformatted we will never know. Are you sure you had if formatted in fat 32 and not fat 16? was there an overlay present from an older system ( these are very fragile)
  5. The bios POST shows UDMA 2 and PIO4 on the HD line. Just for a little history, I started it all because it took 4 minutes to boot up (now takes 1.4 minutes)My Mobo is a PC Chips 571 v 3.2 running on a AMD K6-2/500. The latest Bios upgrade has been installed and I have 128 Meg of SDRAM.

    The HD used to grind away all the time and now (since the reformat) it is fairly quiet and seems much faster. This drive was originally formated with WIN 98 and then upgraded to SE edition before the crash and I re-installed SE directly the second time.

    I got the HD diagnostic program from Seagate (before the crash) that boots from a floppy and it hangs right after it correctly identifies the drive model and starts the diagnostic. The drive seems to operate OK now and I am afraid to try anything again lest I destroy the FAT again.
  6. When you reformatted or run scandisk for that matter did/do you encounter any bad clusters? Are you currently running with dma enabled? I am not extremely familar with your mobo is it a 100 fsb board? Another option could be to pick up a promise ultra 66 card, you can get them on ebay under 20 bucks
  7. BTW the DMA box is presently unchecked in the IDE driver
  8. The FSB is 83 Mhz and the Chipset is SiS 5598. There were no bad sectors on the re-format.

    On the first boot after checking off the DMA option it said to run Regscan and it said to about the two FATs not agreeing. It only gives you the option of replacing 1 with 2 and not the other way around if you so desire. My disk had 2 partitions and the same thing happened to both partition FAT tables.

    I am using this mobo to learn with so that when I finially buy my "dream" system, I will understand the implications of all the different factors and tradeoffs out there. Am looking at the ASUS AV7 mobo but probably want the new DDR SDRAM one just out (AK7-100 ?). I want to ensure that in future (3 yrs) there will be an upgrade path still available.
  9. i would think you would want dma enabled it will give you a performance increase. The problems yu may be expeirancing very well could be due to the fact you are running at 83.3 mhz. This setting is not a very stable setting at all seeing how your pci bus is way out of whack. I suggest clocking down to 75 mhz then enabling dma to see if you have a problem. If no go back up to 83.3
  10. Any ideas as to why the Seagate diagnostic software crashed when trying to test the drive. It knew what drive it was before it started. I am trying to understand if the two events are related. I am satisfied with the drive performance now. I am more curious as to what happened the first time as the results were so disastereous. It took me a full 12 hours to get my system back and I lost a bunch of stuff.

    Whatever reformatting did, it fixed the slow bootup problem and the constant HD grinding. Perhaps it was the attempt at DMA that triggered something in the HD that wasn't active before. I want to proceed very carefully as the risks are very high
  11. it is anybodys guess at this point I still think it may be related to running at 83.3 mhz. Let me know what settings you are running ie fsb voltage,and clock multiplier. Also, having two partitions is kinda a moot point nowadays with fat 32 any reason for this? I would just fdisk and delete all partitions then re partition with only one then reformat. but you will get a 20 percent performance increase on alot of apps with DMA enabled. However, I am leaning towards the fact that your controller is at its limits at 83.3 bus and enabling dma is the proverbial straw that breaks the camels back. Just to humor me kick the bus down to 75 mhz and enable dma. Do you have any benchtest software to actually chart your performace increases/decreases?
  12. Voltage is 2.2V and multiplier is 6. I know I tried testing the drive with the HD diagnostic software with a lower FSB (66) and it still crashed. I do have Partition Magic so can change the partitions without Fdisk. I had originally changed created the second partition in order to try and speed up the boot-up. The reason being that native DOS 7 still only recognizes 2.1 Meg HD and it is patches and OS workarounds these days that allow the larger HD sizes and they all take processor capacity to execute. In reality, I haven't noted much difference but I was desperate at the time.

    I do have Norton Utlilites Benchmark for what it is worth and my system is now at ~124x faster than a 386. The HD performance changed from slightly below average before the crash to slightly above average after the reformat and it increased the system rating from ~89x to the 124x. The original system performance was 42x with the FSB of 66 and a Cyrix MII PR300 CPU, onboard video and 66 Meg Ram.

    I am still leery of humoring you at the possible expense of 12 hrs of my time as I have no means of backing up all my HD short of purchasing another drive (which I may do yet when I have my new system design sorted out).
  13. Ok, lets see you are running 83.3 at 6x thus giving you a 500. However, your pci bus is running at 41.7 mhz. Thus your onboard ide controller is also running at 41.7 mhz while it is designed to run at 33.3. This does not strike you as a potential problem? It is possible to run stable at that speed but if you can consider yourself one of the lucky ones. While your CPU should be safe, writing bad data to the HDD is always going to be a concern do to the highly overclocked controller. I still think overall you stand to gain more performance running at 75 mhz with dma enabled. Also, as I learn more of your system you might want to download a handy little program called CPU idle. Not that I think your CPU is in danger of overheating but it has a handy little side feature. You see you have an older board and many of these older boards bios's do not enable the write back cache of the amd ctx core cpu. This little program, when you choose optimize will enable it for you giving you aprox 20% performance increase. It will also let you now if it is indeed enabled as well as what freq your cpu is actully running at. As for a little better ( not the best by any means, but better) benchmark test try winbench 99 available to download at If you can run thru the full set of winbench tests good chance your system will stay stable. For a quicker test try cpumark99 for on the fly quick comparison's.
  14. Considering I was going to toss the whole thing in the garbage a few months ago, I think it is running quite well and I am quite happy with the new 3x performance. I have another acquantence that has the same board and he has been running over 6 months with these settings with no apparent problems. If I toast something then so be it. That being said, I am still curious from a technical standpoint as I feel the DMA setting should work. The onboad video did die at the higher speed. I have been told that because of asyncronous timing issues between the CPU and the chipset, the board won't run higher than 400 Mhz with the K6-2 with a PCI bus of 33 mhz. The only cards that seem to really struggle at 41.7 Mhz are the older sound cards. Video cards, ethernet cards and even a UDMA66 card show no apparent problem. As I have decent onboard audio, this is not a problem

    You may well be correct in your assertion. I will try the CPU idle pgm (if I can find it) Thanks for your advice. The only program that I run that even exercises my CPU now is full screen streaming video over ADSL and I have a fairly decent fan on it.
  15. I have confirmed what you say is true(both the CPU cache and DMA problem)through another friend in Europe who happens to be a Bios Engineer. I also was told of another program for manipulating the K6-2 and K6-III which is totally free, setk6.

    (found here: )

    I haven't decided whether or not to change the DMA setting as I do very little on this computer that writes or reads a lot of data so I think I would benifit more from a faster CPU than a faster HD.
  16. Setk6 is a nice program that I have used as well although it is a little trickier to use ( you have to modify your autoexec and set certain varialbles, but yes it works well and was written by no other than Andreas.

    A little bit of knowledge is a dangerous thing!
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