Double Your Video-1999-08-24-Plus modem hang-ups, Ultra-DMA/66 to the max, and more-Stephen J. Bigelow

Voodoo 3 and DVD

Q: I recently installed a 3dfx Voodoo3 video card in my PC. I noticed that the card has a feature called DVD Hardware Assist. I already have an MPEG decoder card in the system. Can I remove the decoder card and just use the Voodoo3 card instead?

A: Probably not. The Voodoo3 card can't do MPEG decoding all by its lonesome; it merely helps your decoder card during the decoding process, making possible 30 frames per second (fps) playback of MPEG-2 video with no dropped frames. You can learn more about the card's compatibility and capabilities at www.3dfx.com/view.asp?IOID=102.

Modem Won't Hang Up

Q: I'm having problems with my internal HSP MicroModem 56. When I log off the Internet or finish sending a fax, the modem won't disconnect. I usually have to turn off the PC and leave it off for a while to clear the phone line. This problem doesn't happen when the phone line is disconnected. What's the trouble?

A: In most cases, the modem has a problem. Modems use a small relay to connect or disconnect the phone line. If the relay fails, it may refuse to release the connection until power is removed. The solution: replace your defective modem. For modem repair and refurbishing, check out Modem Express (www.modemexpress.com).

Dualing Video Cards?

Q: I'm considering the purchase of a 3D video accelerator board, but what's this stuff about SLI? I know that I can also have more than one 3D accelerator in the system. Can I use both a PCI and AGP accelerator? If I use two PCI accelerators, do they need to be in adjacent slots?

A: SLI means Scan Line Interleaving, and it is closely related to the use of multiple 3D accelerator cards in the same system. When you install two identical 3D accelerator cards supporting SLI, you connect the cards with a special cable. The two accelerator cards then work in tandem, splitting up the "painting" of the image on screen. This almost doubles your 3D accelerator board's performance.

But note the limitations. The first is card type--the accelerator boards must be identical (i.e., both Voodoo3) and use the same slot type (i.e., both PCI). The second is slot position. As a rule, accelerator cards don't have to be installed in adjacent slots. Just remember that the cable connecting them is usually only about 3 inches long.

Detecting Ultra-DMA/66 Hard Drives

Q: I installed a UDMA/66 controller card in my PC so I could get the maximum performance out of my UDMA/66 hard drive. But the controller only detects the drive as UDMA/33. Have I bought a new controller card for nothing?

A: Not necessarily. You may be suffering from improper drive setup or the wrong drive cable.

The UDMA/66 drive may be configured for UDMA/33 by default. Some UDMA/66 drives (such as many from Western Digital) require you to set a jumper on the drive or run a utility to enable the drive's UDMA/66 feature. Check your drive's jumpers and/or obtain the necessary utility from your drive manufacturer.

You could also be using the wrong data cable. Only a special type of IDE cable can support burst data transfers of up to 66MB/sec. These 80-wire/40-pin cables (usually included with the drive) have twice as many ground wires as traditional 40-wire IDE cables, which dramatically decreases the signal noise a standard cable would generate during 66MB/sec transfers. If you're not using a UDMA/66 cable, the UDMA/66 controller will automatically downshift to UDMA/33. Install the proper cable for UDMA/66 operation.

Checking for Modem Faults

Q: I've used a Practical Peripherals 8600US 56Kbps external modem for over a year without trouble, but suddenly my PC doesn't detect it. I tried removing and reinstalling the modem to the same (and different) serial ports, yet the problem persists. I noticed that when I turn on the modem, the MR and HS LEDs are red (whether it's connected to the computer or not). All the other lights are off. How can I fix my modem?

A: The MR light indicates that the modem is ready, and the HS light indicates that the modem is set for high speed communications. If both LEDs light up, your modem has passed its internal power-on test and is ready for 9600+ work. Given the sudden "loss" of the modem, it sounds like the transmit circuit may be damaged.

Inspect the serial cable between the modem and COM port, and make sure the connection is secure. Check the COM port settings in your PC's CMOS Setup and verify that your COM port is enabled. If it isn't, enable it, save your changes, and reboot the PC so that they take effect.

Now go to a DOS prompt and test the modem by typing ECHO ATA > COMx where x is the port number your modem is installed on (i.e., COM1). Press Enter. If the TR (transmit) LED doesn't come on or the modem doesn't go off-hook, then the modem probably isn't functioning properly and should be replaced. If the TR LED does come on, the modem is working. Check the modem's settings in the System control panel (click the Device Manager tab, the modem item, and then the Properties button). While you're at it, download an updated modem driver from the vendor.

Booting a UDMA/66 Hard Drive

Q: I just upgraded my PC with a Promise Ultra66 controller card. The installation went fine, but now I can't boot from the hard drive. Is the controller defective?

A: This problem is fairly common when replacing or upgrading drive controllers (especially SCSI controllers), so you'll need to do a little detective work to see how serious the problem is.

Boot the system from a floppy disk and try accessing the hard drive, running programs, or copying files between the floppy and hard drive.

If you can't access the hard drive, chances are that there are subtle differences in LBA translation between the original controller and the new UDMA/66 one. This causes the drive's contents to be unreadable. Restore the original controller (which should make the drive accessible again), back up the drive, and reinstall the new controller. You can then repartition and reformat the hard drive using the UDMA/66 controller and restore your files.

If you can access the hard drive after booting from a floppy, chances are that the Master Boot Record (MBR) on the disk is unreadable for some reason. Here is how to reset it:

Boot the system from a floppy to a DOS prompt.

Type FDISK /MBR at the prompt.

Type SYS C: at the prompt.

Reboot the system.

While this trick shouldn't cause any data problems, there is a possibility of data corruption, so make sure that you have any important data backed up be fore attempting the procedure above.

Stephen J. Bigelow is the author of Troubleshooting, Maintaining, and Repairing Personal Computers: A Technician's Guide and 12 other PC-related books from McGraw-Hill. Bigelow is also publisher of The PC Toolbox trouble shooting newsletter. Visit the newsletter site at www.dlspubs.com. E-mail questions to him directly at sbigelow@cerfnet.com.