DXDiag, DX versions, and what your computer can do

DXDiag is this great diagnostic for your gaming hardware. It was created during my time as DX SDK PM by the DX SDK and Tools team. It is hard to imagine gaming before DXDiag and its reporting what is on your machine; but lately I have seen a lot of misunderstanding what DXDiag is and what it does.

DXDiag is a tabbed application that presents information about your gaming hardware.

The front page is the "System" tab and provides general information about what is installed on your machine.

There are tabs specific to DirectXFiles, Display, Sound, Music, Input, Network. and More Help. Each of these specific tabs provides detailed information on that component and all but the Input tab have "Test" buttons to allow you to test the gaming functionality. The results of those tests will inform you as to what the max DX version you can successfully run is. Go to the Graphics tab, and based on the versions it lets you test and what versions pass the test, that defines what Windows thinks your hardware *can run*. Not installed, but what is actually supported by your hardware.

If you are translating what DXDiag says is the highest level of DX installed on your machine, as shown by the data contained on the 1st tab of DXDiag, into what us being used or running - you misunderstand DXDiag. The front tab of DXDiag is informative only, so that is what you *have installed*. DXDiag on Vista will report DX10 is installed even if you have only a DX9 graphics card because DX10 is installed on Vista by default.

That still doesnt mean you are running DX version N. Now it is up to each app to detect what the hardware *can run* and then instantiate an instance of a graphics engine *to use* the hardware.  Since most of the previous versions of DX are available, there is nothing to stop an application from using DX7, for instance, on your DX9 hardware.

So unless you know exactly what renderer a specific game is using, you cannot state what you are running unless you are on Vista. Vista itself uses DX9.Ex or DX9.L to render the desktop, the windows, and the other UI elements. Thus on Vista DX9 *is always* being used.

XP uses GDI, and thus does not get full benefit from the video card like Vista does.

And just for the record, FSX-SP2 ( and Acceleration ) have both a DX9 and a DX10 renderer, and will detect what hardware you have. If you are on Vista with DX10 hardware, you will get the 'DX10 Preview' checkbox. No Vista, no DX10 hardware, no checkbox.

Comments (23)

  1. pepe6859 says:

    I just joint. Not sure whre to post, but wanna say that i’ve been reading all over the net before expend a lot of money on a huge PC able to carrie on with FSX.

    In the past I did it 2 times and as I can see now, things still the same, FS is always to steps ahead available hardware technology.

    BTW I’ll like to say that on this waiting time for the big hardware jump, I intalled FSX on my HP Pavilion 6500 notebook for testing. My surprise!!! Centrino duo 2.2, 2 meg RAM, Vista 32, Nvidia GeForce 8400M GS 128 RAM dedicate, 767 shared for a total of 895 available graphic mem. VISTA SP1 SFX SP1/2 not acceleration. 25 FPS all sliders mostly at 75%, water 100%. So I can fly with not big issues and very smooth. Only when Directx 10 activated FSP drops to unusable low levels. So when in not DX10 mode everything gos good. Why them huge 8000, quads and top of the line hardware can not gives 100% performance?

  2. ice_f102 says:

    In my humble opinion, I believe that FSX is an unfinished product, like Windows Vista. I think you should devote more time to optimize FSX instead of wasting time saying nonsense.

    I bought the 2 FSX versions (regular and deluxe), I bought the Acceleration Pack, and I feel cheated, because I have a computer with a hitech graphics card valued at more than $700 and not get a good frame rate.

    Every time I am more convinced that you are crooks.

  3. pepe6859 says:

    Crook, a slang term for a criminal or a person of questionable morality. Specifically it refers to someone who is corrupt and uses dishonest or unethical tactics to gain money. The adjective crooked can refer to such persons or actions. This version of the term may also be archaically used as a verb in reference to becoming a criminal or causing another to become a criminal.

    How can you tell that to me, if you don’t even knows me? I just post my opinion acording to my results, thats all.

    Why are you giving me the oportunity to think you are suffering fron fragile X syndrome.

  4. jahman says:

    Hi, Phil!


    XP uses GDI, and thus does not get full benefit from the video card like Vista does.


    Could you provide an explanation?  (blurb or url)



  5. anony.muos says:

    Are you sure you ran DxDiag on Vista at least once, because on my comp running Vista, I see no buttons to test ANY of the functions, which drove me completely mad. Another Vista feature removed silently?

  6. Phil Taylor says:


    Vista uses DX9.L to render the Aero interface on the GPU in 3D.

    XP uses GDI to render the XP shell mainly on the CPU in 2D.

  7. Phil Taylor says:


    its a game. if you were that unhappy, you should haved returned it.

    have a great Holidays.

  8. anony.muos says:

    So is the testing ability removed? Why? Wasn’t it useful for troubleshooting? Okay, DirectSound got removed but what about DirectMusic, DirectInput, DirectPlay and Direct3D 10? No test for Direct3D 10?

  9. Phil Taylor says:


    I dont have a DX10 machine at home to fully verify and this is not a high priority for me during the holidays. take some time off and come back in a week or so.

  10. it's me says:

    I must admit being an end user I have been using DxDiag since the year dot and have never found one bit of use for it yet. DX10 preview gives me about 8fps more than running FSX without it so I am more than happy…

    Vista™ Home Premium

    AMD Athlon(tm) 64 X2 Dual Core Processor 5200+, 2612 Mhz


    Corsair 3GB RAM

    NVIDIA GeForce 8800 GTX

    Creative X-Fi Fatal1ty

  11. mtoohill says:

    originally posted by Phil Taylor 12/30/2007 in response to ice f102:


    its a game. if you were that unhappy, you should haved returned it

    have a great Holidays."

    Phil, I assume you know that an end-user cannot return opened games.  Once you buy them and open them, you’re stuck with it.  You are really not aware of this?


  12. blueflamer says:

    yes, I would also like to return, please explain how?

  13. Te_Vigo says:

    Phil, in Australia it is illegal to return opened software, unless the disc is damaged in which case a replacement can be given.

    Once it’s bought, you’re stuck with it

    and yes, with (at least) Vista* Home w/ PCI Express the VGA and Sound test buttons have been removed from dxdiag.

  14. Te_Vigo says:

    Also in the link supplied, under the section:

    What Products are not Eligible for Refund

    Products no longer actively sold or technically supported by Microsoft.

    the point seems to conflict as FSX is no longer actively technically supported… is this correct?

  15. Phil Taylor says:


    read the link.

  16. Phil Taylor says:


    I cannot help with national laws, I am just pointing out a common misconception wrt MS products and refunds

  17. Phil Taylor says:


    wrong, that refers to products past the 7 year product lifecycle.

    do not confuse the fact we are making no more service packs with not supporting FSX.

  18. Phil Taylor says:


    you get 1 comment on this blog, not 3. time to move along.

  19. Te_Vigo says:

    Thank you Phil for the clarification on my question

    as for national laws, we do understand that you personally cannot do anything about them… the common misconception was in under what conditions the product can be returned.

    Though you do not control what goes on the box, a I feel simple way in which no return laws can be bypassed is to have printed clearly on the box wording to the effect, in it’s own clearly legible section, of ‘This product can be returned for a full refund at point of sale or by returning to local Microsoft for any reason, within determined timeframe yada, yada, yada’

  20. ArchCarrier says:

    "do not confuse the fact we are making no more service packs with not supporting FSX."


    I break my silence one more time and hopefully for the last time.

    For the sake of clearing this up once and for all can you please clarify what this statement means?

    No more service packs, is clear, but what does the future support for FSX entail? For instance will there be further small patches fixing long term bugs in the retail version of FSX, the bugs created by SP1 and the bugs created by SP2?

    I am sure that there are many FSX users who would like to know what the word "support" actually means in the context you are using.


  21. Phil Taylor says:


    "Support" as I am meaning here is does Product Support take a call on a product or not. And that is what the MS returns policy is talking to as well; which is what started this part of the discussion.

    MS provides clear guidelines on what the lifecycle of a product is and when it ages and fall off of the support list.


    And specifically for FS Acceleration:


    There is more to support than producing service packs so please do not conflate the two.

Skip to main content