Review Date: July 1998 (Updated: 11/4/99 for Mac Tests)

Quantum 3D's Obsidian2 X-24 Single Board Voodoo II SLI

I used 3Dfx's beta 2 Voodoo2 drivers (see my previous review of these drivers) with the X-24 in my Apple G4/450 AGP system. As noted here in my original review of the X24 in a PC - these cards run hot and may not be a good choice for many Macs without added cooling. The G4 case, like the B&W G3s, has a large fan blowing on the PCI slots which seems to help. In limited tests so far at 100MHz (using a Voodoo2.var) file I've seen no problems. As noted in my Voodoo2/SLI article, Quake1 doesn't run but Unreal 224b7, Quake2 and Q3test1.08 ran fine with excellent performance. Scores from the stock Rage128 AGP and a 166MHz Voodoo3 AGP card tested in the same G4/450 AGP system are included for comparison:

For Mac owners with a single monitor who don't want to lose DVD player functionality but still want better game performance than the Rage128, a Voodoo2 is still an attractive option. As noted in my original Obsidian X24 review, the 'medusa' passthru cable had poor monitor image quality at higher resolutions, but looked OK here on an IBM LCD at 1024x768 (running it on a non-LCD would be a better test of sharpness however). For more on Voodoo2 and SLI mode, see my Voodoo2 review posted several months ago when the 3dfx Mac drivers were first released.

Introduction:
A few months ago I posted a note in the news about the announcement of this card, a single board dual Voodoo II card that does SLI (Scan Line Interleaving) in one PCI slot. I asked for readers to write Quantum 3D (many of you did) to ask for a Mac version. Recently I repeated the request since a reader said they were still considering offering a Mac version, if enough interest was present in the Mac community. Quantum 3D makes standard Voodoo II cards as well as this and other higher end 3Dfx Voodoo chipset based cards, some with drivers for 3D Studio Max and arcade machine applications. So even if you're not interested in a high end (read expensive) card like the Obsidian X24 it would be good to see another Voodoo II offering. Granted with the reported entry of Techworks and VillageTronic into the Voodoo II/Mac market there might be more vendors than the market can support.

Although the current product is PC only, I wanted to post this page to make Mac owners aware of how the card performs and the pros and cons of a single card SLI approach. Even before seeing the card I was concerned about thermal issues with a piggybacked dual Voodoo II card with no fans, especially with a 90-95MHz design and the inverted design of PCI cards where chips are on the bottom of the card (installed), which does not help heat dissipation as heat is radiated back onto the card rather than away from it. It turns out my fears were well founded.

What's Included:
Unlike most PC Voodoo II cards now, the Obsidian 2 X24 does not come with any full game versions only two CDs with 14 demos of the most popular 3Dfx Glide (native 3Dfx API) and Direct 3D (Microsoft's API) games. The other included CD-ROM has the Windows 95/98 drivers, NT 4 drivers (including service pack 3 in case you need it - as its required for Direct-X support in NT 4) and Direct-X version 5 installer. The thin manual was adequate but contained a few errors - my OSR 2.1 Windows 95 did not have the same installation procedure as was noted in the manual. OSR 2.5 does I believe. The cable supplied with the Obsidian is like no other, called a 'medusa cable'. If you note in the card photo above or in an end view of the card you'll see it has only one connector, not two like most 3Dfx cards. The Medusa cable is needed as the single connector on the Obsidian has 26 pins - separating the VGA input and output in a single connector. This saved space needed for the TV out composite and S-Video connectors on the card.

I did note the Medusa cable appeared to have no shielding on cable section from the output of the 2D video card to the Obsidian. The output cable appeared to be larger diameter cable and from the stiffness I assumed it was shielded. Quantum3D admits to image degradation that sometimes occurs in 3Dfx cards due to passing the 2D Video through the card. Their FAQ notes this most often occurs at 1024x768 or above and can be helped in some cases by changing the refresh rate of the 2D card, straightening out the pass-thru cable or moving the Voodoo card to another slot. They also offer another solution to avoid the problem - if your monitor has dual inputs (BNC and std DSub) you can run a BNC cable from the 2D video card to the monitor's BNC connectors and a std VGA cable from the DSub connector to the Medusa cable of the Obsidian. You'd then switch the input source of the monitor as needed or if you're lucky, the monitor will support auto-sensing and do this automatically. This is the best solution as there is no loss of 2D video signal sharpness and clarity.

Installation:
Despite following the instructions to the letter (removing all traces of my previous Creative Labs Voodoo II card from the device manager, etc.) the install was a rocky one. Windows 95 detected the Voodoo card before detecting a 'multimedia device' - so the CD's inf file was not recognized, even when I pointed directly to the file/directory on the installation CD (the infamous "this file does not have information about your hardware" or similar message). I finally ended up right-clicking on the INF file and selecting install. That resulted on two entries in the device manager but not a correct install. Rebooting did not help so I deleted the two entries (both Voodoo II chipsets are shown) in the device manager, shut down and rebooted. This time the install went as it should and I was off and running. Note that the resources for both the Voodoo II chipsets in the device manager show as a conflict with the motherboard PCI Bridge - that's normal according to the manual.

After a proper install the Windows 95 display control will have a new tab called "Obsidian 2" as show to the below.

Controls:
The Obsidian 2 control panel is very complete except for one option that may be sorely missed for compatibility reasons - there is no Disable SLI mode option. Some games currently do not run in SLI mode and I'd like the option to disable SLI as a way to compare the benefits of the 2nd Voodoo II chipset. I wonder if this is the reason they don't provide a way to disable it, as some games show as little as 5% boost (others more than 70%). As a minimum, SLI mode allows running resolutions of 1024x768 in games that support it like Quake, Quake II, Unreal and Forsaken. From my tests in a PII 300, the card ran just as fast at 1024x768 as it did at 640x480. It's obviously CPU bound in the PII 300 at least. A PII 400 or better is needed to begin to reach the capability of this card, but there were obvious benefits even with the PII 300. Running 1024x768 at the highest quality settings as fast as a 12MB single Voodoo II card at 800x600 was one of them.

Note the Obsidian 2 control has a Performance slider that adjusts the speed of the card and that it defaults to 92MHz, 2MHz higher than the standard reference card designs. Due to the heat issues I saw I did not attempt to run the card at faster speeds, as a fan was needed for reliability at the stock setting (more on this later). The control also includes gamma settings, separate Direct-3D and Glide settings for resolution and refresh rate and the option on each to disable waiting for vertical blank (retrace). Leaving vertical retracing sync on ensure you will get no 'tearing' of images in games where the frame rate exceeds the vertical refresh rate of the display. Each area of the control has a 'Test' button to allow you to verify that the card is functioning properly. The TV Settings button allows you to select 640x480, or 800x600 display modes and to enabled mirroring (a nice feature that allows you to play a game and record it at the same time on a VCR).

One Hot Card:
As I mentioned earlier, my initial concern was how hot the card would run, especially with games like Unreal that already has a reputation for locking up single Voodoo II cards. I found it odd that the issue of cooling is literally not mentioned in the Obsidian 2 manual but it was something that became an issue very quickly when running Unreal at 1024x768. After running Quake II for about 15 minutes or so, I ran Unreal at 1024x768. Within 5 minutes the game locked up, forcing a restart. Textures and text began to show corruption shortly before the card froze. I then installed the 'maximum quality' autoexec.cfg for Quake II from three fingers as a stress test. This config file sets all quality settings to maximum for the best possible display quality (at the cost of framerates). I then ran Quake at 1024x768 for about 30 minutes. Again I saw the card freeze due to heat. The PII 300 full tower system had been running for about 3 hours now. I powered down and removed the cover to check temperatures. The Obsidian 2 card was so hot I could not keep my hand on even the back side of the pc board. I've never seen a card get this hot before.

The PII 300 system is a full tower with 300 Watt power supply. It contains a fan on the PII 300 heatsink, a fan above the PII that blows down on the large CPU heatsink and a fan in the ATX power supply. The case is large with lots of free space, but almost all slots are full. The lower two slots are ISA (Industry Standard Architecture) filled with a 56K X2/V90 USR modem and a Creative Labs AWE-32 sound card. Next up was the Obsidian2 card, then a Diamond Monster Sound PCI card. Above that is a Diamond FirePort 40 Ultra-SCSI PCI card and finally in the AGP video slot is a Diamond Viper V330 (Riva 128) graphics card. There was one free PCI slot (a 4th) but it is a 'shared' slot with the topmost ISA slot, usable only if no ISA card in installed there. This system was an example of why people buy the single board SLI cards, there was no free PCI slot to allow a dual Voodoo II card setup as is the normal way to run SLI mode.

Internal PCI Card layout of the PII 300

Solution:

After checking my parts bin I found two 12V DC fans. The first one I tried was a low quality, cheap fan I'd bought at a PC show years ago. It did not have a CFM rating (Cubic Feet/Minute) but I knew from feeling the airflow from it that it was not adequate. Tests proved this was correct, it offered little to no benefit. The 2nd fan was a higher CFM (again by feel), higher quality Panaflow© model that did make a big difference. The problem was mounting it, especially at the proper height/position. Again digging through my parts bin I found 4 adhesive backed tie-strap anchors and straps. Sandwiching these between a 3.5" floppy blank front panel cover provided the perfect height.

Clicking on the image below will show a full size image with a clearer view of the fan and home-brew mounting arrangement. It's not pretty but it works, and that's all that matters.

After installing the fan and closing the case I again ran Quake II at 1024x768 with the maximum quality settings. After an hour of play there were no problems whatsoever so I moved on to Unreal. I ran Unreal again at 1024x768 for more than an hour with no lockups. I did see some cases of image corruption at times (not consistent) on text, the weapon and on the halo of bright lights. A sample of this can be seen on some full size images linked on the Unreal screenshots page. This could be a bug in Unreal or the current Obsidian2 driver but I suspect that it is the heat issue again. I will try more tests, possibly with the card set to 90MHz to verify this.

I saw no lockups at 92MHz with the fan running in about an hour of constant play in Unreal. After about 2 hours of gameplay (Quake and Unreal) I shut down and removed the cover again to check the card - it was much cooler. Warm to the touch but not uncomfortable to hold. A dramatic improvement over the test with no fan in which the card was too hot to touch for more than a second or so.

Note I discarded the idea to use a side mounted fan like the original 3Dfx Cool since it would provide less card area coverage than one mounted on the end, blowing down the length of the card. Since the two voodoo II PWBs (Printed Wiring Boards) are closely placed (only about 1/4" apart) a fan blowing edgewise is a better choice for this particular card in my opinion.

I'll try to do more Unreal tests to see if the image corruption is consistent with thermal temperatures of the card. I may reinstall Unreal and apply the beta209 patch as well. I'll also run a 2 hour long Unreal test to ensure the fan does solve the problem. Bottom line is that in my opinion this card needs a *good fan* to operate reliably.

Now that I've bored you to tears with the heat issues of the card, the next page shows framerates and screenshots in Quake II and Unreal at 1024x768.

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