processor upgrades Graphics Cards

New Software Brings XLR8 Card Up To Speed XLR8's G4/350 MACh Carrier Card Review Update


Don Engstrom, Reviews Editor

Review Update: Our initial review of XLR8's MACh Carrier G4/350 card was a frustrating experience to say the least. We spent several weeks trying to track down the cause of repeated crashes and boot problems. With the help of XLR8 we discovered that the problems stemmed from running the card with "write-through" mode disabled. Check out the side bar below for an explanation of write-though. Unfortunately, in version 1.4.2 of XLR8's control panel write-through is disabled by default and the option to enable it is hidden. Enabling write-through fixed all of the stability problems but caused a performance hit. XLR8 has since released version 1.4.3 of their software so we popped their card back in our 9500 and put it through its paces. The updated scores below show that the revised software has brought XLR8 back up to speed and right on par with the competition. We have left our original review in place but have posted amendments to the text in red.

General Impressions: We have always enjoyed receiving XLR8 cards for review. We have always found their G3 cards to be stable and easy to install. I also appreciate the ability to fiddle with a card's settings to push its performance to the limit. When XLR8 sent us their G4/350 Carrier Card for review we expected a similarly pleasant experience. We were unfortunately disappointed, at least at initially.

Software Installation: XLR8's installer places the usual extension and control panel in their respective folders. XLR8 also provides their own AltiVec (aka Velocity) plugin for use with Photoshop 3.x and 4.x. boosting the speed of certain operations by up to 300%. See the "AltiVec Enabled!" sidebar below for more information. The control panel provides information on current settings and allows you to adjust the backside cache speed and toggle the following on or off:

  • power conservation,
  • speculative addressing
  • motherboard cache.

Another setting which is unfortunately hidden by default is the "write-through" state of the backside cache. We will go into this in detail in our stability section. [Write-through is now visible and on by default. Attempts to disable write-through result in a warning about stability issues along with instructions on how to re-enable it should you run into problems]

Speculative addressing, also called speculative processing has been the subject of heated online debate after Newer Technologies released a "white paper" warning of data corruption, boot problems etc. if speculative addressing is not turned off properly. This was followed by a rebuttal from XLR8 andPowerLogix. Newer takes a hardware approach to dealing with the speculative addressing issue, turning off speculation in input/output space but leaving it on in RAM/ROM space. The other manufacturers take a software/firmware approach. The issue with the software fix is that the patch can be erased in the unlikely event you "zap" your NVRAM. You should note that NVRAM and PRAM zaps are two different beasts and zapping your PRAM (a useful troubleshooting procedure) will not remove the SA patch. XLR8 now provides an emergency startup floppy which will boot your machine and restore the NVRAM patch if needed.

Hardware Installation: XLR8 wins the prize when it comes to helping you through the installation process. Their documentation is well written and comprehensive covering all of the appropriate machines. In the past, their chart outlining all possible speed settings may have been a little overwhelming for some. Their latest documentation now thankfully includes a trimmed down chart with just the most common settings. The full chart is still included as well for the adventurous. XLR8 continues with its fine tradition of including a high quality, reusable grounding strap to help avoid static mishaps.

Performance/Stability: The XLR8 card was the first G4 to arrive on our doorstep so we didn't have an idea what to expect in terms of performance or stability. The first reboot after install was successful so we proceeded to run through our benchmark run. Unfortunately we ran into problems when we attempted to run Unreal frame rate, MacBench 5.0 and the SoundJam encode tests. On each application the 9500 repeatedly crashed requiring a reboot. We also had sporadic problems getting the system to boot. Fortunately in this case we tracked down outdated FWB disk drivers as the culprit. We reformatted with Apple's latest drivers and the boot problems disappeared entirely. The system continued to crash when running the above applications though and we went through a variety of troubleshooting efforts to resolve the problem including the following:

Reformatting the drive and installing a fresh copy of OS 9

Installing four AltiVec specific extensions off the OS 9 CD using the Tome Viewer application

Lowering the system bus setting

Running off a drive with OS 8.6 installed

Installing the software that PowerLogix provides with their G4 cards

Only the last two setups yielded favorable results. The card seemed stable both under OS 8.6 and when running the PowerLogix software. Conducting a review under an older system software or using a competitor's software is hardly ideal though. [running under version 1.4.3 has been very stable so far. We have not experienced any of the problems mentioned above]

Write-Through Mode Explained

"write-through is a cache operation mode. Every time data is stored to the L2 cache, it is also *immediately* written back to main memory. This means that cache lines are never "dirty", i.e. main memory always matches what is in the cache.

Obviously having to write every modification back to main memory every time will impact performance, usually by about 10% and this is the reason we do not turn it on by default."

-Chris Cooksey, Director of Software Engineering, XLR8

After numerous messages back and forth with XLR8's support and engineering team we stumbled on the solution to the stability issues. Hidden in the control panel is an option to set the backside cache to "write-through" mode. This checkbox option can be accessed by holding down the option key when selecting the "Advanced" tab in the XLR8 control panel. [See note above. Write-through is now visible and on by default] I have been running the card with this setting for several days now and have not experienced one crash. I have rebooted several times and run a variety of applications all of which seem stable. The sidebar to the right explains what write-through is in detail. It would be interesting to run comparative benchmarks with write-through enabled and disabled. Unfortunately, disabling write-through is not an option, at least not on our 9500 under OS 9. Comparing the XLR8 card with write-through enabled to the PowerLogix G4/350 we recently reviewed (also with write-through enabled), we noted the XLR8 card ran between 2% and 20% slower than the PowerLogix card. We also ran the XLR8 card using the software package from PowerLogix. While we didn't conduct any real world tests with this setup, MacBench showed a 19% difference in processor score and 7% in FPU. Check out the MacBench scores below for performance information at a variety of settings and configurations. [Version 1.4.3 brings XLR8's card right on par with PowerLogix and others. Check out the scores below for a comparison of 1.4.2 vs 1.4.3. We will also post updated results to our G3/G4 upgrade card overview in the next few days. It is also worth noting that I was unable to overclock this card to 400MHz without repeated crashes.] Interestingly enough, we were able to use the XLR8 software with write-through disabled just fine under OS 8.6.

AltiVec Enabled!

While the rumors have been flying about Adobe posting the AltiVec enabling software on their site, the ETA for this posting has come and gone. We have heard (indirectly) from Adobe that the software has been submitted for posting and should appear in the near future. At this point it is unclear whether Adobe's software will be limited to Photoshop version 5.5 or if it will cover all versions of Photoshop 5. XLR8 includes their own AltiVec plugin that will work with versions 3.x and 4.x of Photoshop. While the plugin doesn't boost performance across the board, it provides amazing results for the following key operations:

  • Blend Color, Blend Gradient Tool
  • Blur, Blur More, Blur Motion, Blur Radial, Blur Smart, Gaussian Blur, High Pass, Motion Blur
  • Despeckle, Feather, Find Edges
  • Rotate, Rotate Canvas 180, Rotate Canvas 90, Rotate Canvas Arbitrary, Rotate Canvas Flip Horizontal, Rotate Canvas Flip Vertical
  • Sharpen, Sharpen Edges, Sharpen More, Unsharp Mask
  • Image Size, Resize, Canvas Size
  • It is not clear whether all machines will need to enable write-through for stable performance. However, I believe it is a big enough issue that XLR8 should set write-through as the default and let users try running with it off. Hopefully this will be the case with their next software release. At very least, the write-through check box should be visible and enabling write-through should be added to the troubleshooting section of their documentation as a potential fix.

    As we mentioned before, XLR8 provides an AltiVec plugin for Photoshop, versions 3.x and 4.x. We ran our Photoshop tests with and without the plugin and the performance gains were very impressive! Some filtering operations completed roughly 4x as fast when using XLR8's plugin! As with other G4 upgrade cards, you will need to run applications that have been optimized for AltiVec to see this kind of striking performance gain. If you are running applications that have not been optimized for AltiVec the G4's are roughly equal in performance (MHz for MHz) to the G3's. After we have completed all of our G4 reviews we will put up a page with scores comparing all of the cards.

    Conclusions: All of the stability issues we experienced early on seemed to arise from running the card Under OS 9 with write-through mode diabled. It is unclear at this point whether enabling write-through caused the performance hit we noticed. Running the card using PowerLogix software (which enables write-through by default) provided stable performance without an apparent performance impact. Based on this information I think it is safe to assume that the XLR8 software is somehow hampering the card's performance. Hopefully future revisions of XLR8's software will resolve the stability and performance issues we noted in this review. If we are able to conduct tests with new software we will update this page with our findings.

    Revised Conclusions: All of the stability problems we noted in our original review were traced to the disabled write-through mode of operation. The performance hit we noticed with write-through on was related to some early (and now unnecessary) software code which has since been removed. It looks like we are finally able to give XLR8's card a clean bill of health!

    Test Machine Configuration

    Our test machine was a 9500 with 96MB RAM and OS 9 installed. We tested with an extension set comprised of all OS extensions plus those installed by XLR8 and, for some MacBench tests, PowerLogix. For the MacBench tests virtual memory was turned off and disk cache was set to 512k. These settings are consistent with those used on the MacBench base reference machine, a beige G3/300. For the real world tests we turned virtual memory on and set it to 97MB.

    Product: MACh Carrier G4/350/175/1MB
    Company: XLR8
    Rating: (5 possible)
    Hits: Includes Photoshop 3.x and 4.x plug-in which provides excellent performance gains, carrier design reduces future upgrade costs by allowing the use of ZIF processor cards, well written documentation.
    Misses: Unable to overclock to 400MHz

    MacBench 5.0 Scores

    MacBench 5.0 is a subsystem-level benchmark that measures the performance of a Mac's processor, disk, and graphics subsystems to name a few. MacBench normalizes all scores relative to the base machine, a Power Macintosh G3/300. The base machine receives a score of 1000. For all MacBench tests, higher numbers mean better performance. For more detailed information on MacBench click here. Remember, MacBench 5.0 came out well before the G4 processor and was consequently not written to take advantage of or test the AltiVec (AKA Velocity) instruction set. Since we ran MacBench under a variety of different card settings and OS versions we have spelled out these configurations below.

    Test Configurations
    Card Settings & Software Version Operating
    Backside Cache Setting Notes
    XLR8 G4/350/175/1M v1.4.2 OS 9 Enabled 175MHz (2:1 ratio) This was the setup we used for all of our "real world" tests below. Ran very stable with this setup.
    XLR8 G4/350/233/1M v1.4.2 OS 9 Enabled 233MHz (3:2 ratio) Ran fine, only used for MacBench testing.
    XLR8 G4/350//175 PL Software OS 9 Enabled 175MHz (2:1 ratio) Using software from PowerLogix. System appeared stable. No significant performance hit.
    XLR8 G4/350/233/1M v1.4.2 OS 8.6 OS 8.6 Disabled 233MHz (3:2 ratio) Ran fine even with write-through disabled.
    XLR8 G4/350/175/1M v1.4.3 OS 9 Enabled 175MHz (2:1 ratio) Using new XLR8 software, version 1.4.3. Card was stable and performance on par with other G4 cards in its class.





    "Real World" Tests
    (Shorter bars are better)

    Time to Scroll a 574 page AppleWorks document from top to bottom.

    Using the same document as above we did a search/replace command to replace the word "the" with the word "macbench," over 12,900 occurrences total!

    Photoshop 4 "Real World" Test Results

    All scores are relative to the stock 9500 which was assigned a score of 100. Lower numbers and shorter bars are better. Obviously, the first three tests are filter operations that can make use of the plugin and the rest are not. We ran these tests both with and without XLR8's Velocity plugin for comparison.







    Render Boy 2.2.0

    Time to render "Pool Table" Example file

    SoundJam MP3 Encode

    Time to encode a CD track 4 minutes 26 seconds in length. for this test we underclocked (blasphemy!) an XLR8 G3/400 to 350MHz. Scores are absolute (time in seconds) and, of course, shorter times are better...

    Card Stats.

    Manufacturer -Card


    Cooling System

    Variable/Fixed Clock Rate

    Tech Support


    XLR8 MACh Carrier G4/350/175/1MB PCI
    With ZIF Daughtercard
    Heat Sink Variable

    Toll Free Phone
    316-636-4616 Fax

    2 Years