The nForce PCI writes mystery

Since I purchased the MSI K7N420 Pro motherboard late last year, I've participated in one form or another in the MSI nForce forum. During that time, there has been a complaint or two about low write performance from hard drives, in particular with IDE RAID. The nForce boards' peak write speeds on drive benchmarks using PCI disk controllers would never crest over 20MB/s, while read scores have hit as high as 113MB/s. Due to a relative lack of complaints and the fact that most users were using Windows XP, which has its own hard drive writes performance problems, the issue was largely ignored.

In light of some recent tests from SCSI and IDE RAID users from Windows 2000, it's begining to seem that there is a problem with nForce, not just with the OS. In fact, Asus apparently has taken steps to address the problem. Among the fixes in Asus' latest beta BIOS for its nForce board is a correction for poor PCI write performance.

Despite a benchmark or two from MSI users and some reports from Asus users, the overall picture remains spotty. The MSI nForce forum doesn't have a large enough user base to prove that PCI writes are limited to 20MB/s. Nor does the forum have the resources to show whether or not this writes issue is limited to just MSI's model or to the entire nForce chipset. So I need the community at large's help to determine whether or not this issue actually exists and with which boards.

If you own one of the nForce boards from Abit, Asus, MSI, or Leadtek and you use a PCI IDE or SCSI controller, please take the time to download ATTO's disk benchmark and run it. Go here and enter a name and e-mail address. Then choose the "Select" button to the right of "ATTO ExpressPCI HostAdapter Utilities" and select to download the "Windows SCSI Utilities Version 1.63" from the drop down menu at the bottom of the page. The file that begins to download should be EPT163.exe. Here is an example of a WDJB100B drive's results using the appropriate test settings (I was using the south bridge chip's controller here, so write performance is fine in the example).

Once you have installed the software and configured it to the above example like my sample picture, run the test. After the benchmark finishes, post a comment with your board brand, BIOS revision, controller model and driver, OS, and the scores themselves. For example:

  1. MSI K7N420 Pro, BIOS 2.4

  2. Promise 100TX2,, and

  3. Windows 2000 SP2

  4. 64k:Write:X Read:X

  5. 128:Write:X Read:X

  6. 256:Write:X Read:X

  7. 512:Write:X Read:X

  8. 1024:Write:X Read:X
...where the X's are scores. The ATTO program does not create any Add/Remove Programs entries or registry keys, so you can just delete the folder and program group to remove it.

Remember, this problem will not occur with the nForce's on-board IDE controller. Only drives using PCI IDE or SCSI controllers or the Highpoint controller integrated into the Abit NV7-133R will be affected by this issue. Please be courteous in the comments. The goal here is to figure out what's up with nForce PCI writes. We'll be following up with NVIDIA, as well. Thanks.

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