Microsoft warns against installing 64-bit Office 2010 unless you really need it

Microsoft has released 64-bit Office 2010, at least to MSDN and Technet subscribers, with general availability to follow shortly. Now that 64-bit Windows is commonplace, you would think that 64-bit Office is the obvious choice.

Apparently not. Take a read of this technical note before installing 64-bit Office 2010. In essence, it recommends installing 32-bit Office, even on 64-bit systems, except in the following case:

If some users in your organization are Excel expert users who work with Excel spreadsheets that are larger than 2 gigabytes (GB), they can install the 64-bit edition of Office 2010. In addition, if you have in-house solution developers, we recommend that those developers have access to the 64-bit edition of Office 2010 so that they can test and update your in-house solutions on the 64-bit edition of Office 2010.

That’s a small niche. So what can go wrong if you decide to go 64-bit? First, it might not install:

If 32-bit Office applications are installed on a computer, a 64-bit Office 2010 installation is blocked by default.

says the tech note. In addition, if you manage to install it, you will have problems with 32-bit Access applications, 32-bit ActiveX controls and COM add-ins, in-place activation of documents where the OLE server is 32-bit, and VBA code that calls the Windows API. VBA deliberately disables API calls defined with the Declare statement; they must the updated with a PtrSafe attribute before they will run.

The Office install DVD includes both 32-bit and 64-bit versions, and the 32-bit version installs by default irrespective of the version of Windows.

Of course I will be trying 64-bit Office on a spare machine. I’m interested to know, for example, whether Outlook benefits from all that extra RAM, since it is notoriously slow. But overall, 64-bit Office 2010 looks more like a release to prepare the ground for the future, than one for normal use.

12 thoughts on “Microsoft warns against installing 64-bit Office 2010 unless you really need it”

  1. I’d be very surprised if Outlook (a client program) would benefit from RAM beyond 2GB. It’s disappointing that MS don’t allow 32-bit Office to use a full 4GB on 64 bit systems (through /LARGEADDRESSAWARE).

  2. Well, the Outlook speed issue is mainly for those with huge mailboxes, which can easily exceed 2GB in size. I’d have thought it possible that more RAM could help it.


  3. I’m not sure why Outlook would ever need to load them all into memory at once. Indeed I’m not sure it would make sense to do so. Also, why would MS optimise an unusual use case, that of local mailboxes? Presumably, as has always been the case, their main focus is on Outlook as a client to Exchange.

    Anyway, you can let us know if you notice a difference.

  4. I doubt Microsoft Outlook will be using anywhere near that amount of RAM anytime soon. My Microsoft Outlook data is under 2GB in total, yet I rarely see Microsoft Outlook ever use more than ~130MB of RAM—so this is clearly not a case of Microsoft Outlook not having access to enough RAM.

  5. I’ve been using the 64bit beta and now the RTM version of Office 2010 on W7 64bit with 8GB of ram and I find it a lot faster than 2007 though that was 2007 running on vista. Actually I think the beta was slightly faster than the RTM but thats probably my imagination.

    All in all I’m exceptionally pleased with the look feel and functionality but more than anything else the speed. So far I haven’t had any issues though Outlook would be the app I use most. It is definatly faster than the 2007 version with a 5GB mailbox.

  6. I am using windows 64bit Office 2010. it sucks, it’s really slow, especially email. I have a new c7 machine and 8gig of ram so it’s not a pc issue. Everything else zooms on the machine but I consistently get latency issues when simply trying to read and delete emails in 2010. I can’t believe I wasted my money on this junk. 2007 was much better. In fact I will have to reinstall it 2007 that is (likely). i must say, next time i upgrade computers I am seriously going to look at mac, at-least that don’t use us as R&D rats like bill gates

  7. Office 2010 32 bit is extremely slow on my computer. I have Windows 7 64 bit and 8gb ram. I am trying to work with layers of graphics but it has a 5 second delay between when I select an object to when I am able to continue working with it. That is so hard. I think I am going to try to find another program to work with. I really am under a time crunch and I cannot find a work around for it. Office 2010 64 bit just locks up. Researching it through google shows that as a known problem. If anyone has any ideas as to how I can get this to work, please let me know.


  8. Another thing to consider when installing is that some smartphones currently will not synch up correctly when 64 bit is installed. I know this is a problem with blackberries right now although I’m told they’re working on a fix.

  9. I have Windows 7 64, and been working very stable with Office 2010 64 along with FrontPage 2003. FP2003 is an essential tool for writing my numerous daily logs unfortunately it has not been carried along Office 2010 in a light fast loading app.
    The pain comes I try to install another Office product like
    Office 2007 then I got into a Catch22 loop complaining it I try the 64 version it says I have FP2003 if I try the 32 bit, it says have Office 64 and it cannot be done.
    I had to un-install FP2003 install project 2010 64 then re-install FP2003.

    Today, I am faced again with the same stupid limitation while trying to install Visio 2010 64 or 32.

  10. I run a windows 7 – 64bit bic. Software Developers like the extra oomph. I installed Office 2010 64-Bit. My mail box is over 5GB, I use Excel , One Note, Word, etc. all the time.

    The biggest complaint? NO 3rd party really supports Outlook 2010. MS finally released social connectors for it. Google doesn’t have Sync for it. It seems it’s the child that has been forgotten.

    Oh, and whenever I run Excel it wants to install Visual Basic for Applications.

  11. tangent: I can’t understand why anyone would use outlook 2010.

    Compare how quickly mail can be read in Outlook versus the M2 mail client built into Opera.

    Seriously, the only time I open Outlook is to check the calendar. Then I close it to get my computer back to a usable state.

    Everything microsoft makes is awful.

    Notice how since the advent of SATA drives a lot of software installation wizards run very quickly, until they get to the point of “register this dll with the system”?

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