Question Win7 mbr main + want to install win10 gpt on another drive

eodeo

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I have win7 x64 as my main and I need to install win 10 as my secondary OS. I was hoping a simple dual boot will do, but I ran into problems.

When installing on a different hard drive (not merely a different partition), win 10 gives me warning that GPT will be a problem - or some such message. I noticed that people making dual boot 7/10 tutorials use their main drive, shrink it and install win 10 there. So I tried that too, but win10 is unhappy again saying that it's MBR.

I want to occasionally play Half Life Alyx and for the oculus VR support, unfortunatly I need win 10. My computer is plenty fast, but I don't want to damage the win7 main install. As I understand it, I can't dual boot normally, but I can select boot drive order from BIOS and that way I can switch the OSes. I'm happy with that as I'd only be running win10 seldomly.

My question is- will doing that- installing win10 on a different drive as GPT destroy my win7 main install? Thank you!
 

USAFRet

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Install the Win 10 with ONLY that one drive connected.
Reconnect the Win 7 drive after.

 
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eodeo

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Thank you very much! I have a problem because I don't have a whole HD I can dedicate to win10. I have 300gb partition I planned on using for it, but I need the other partition too. Your tutorial suggests that I need a whole hdd. Does that mean that I could lose the other partition the win10 install would be using?
 

USAFRet

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Thank you very much! I have a problem because I don't have a whole HD I can dedicate to win10. I have 300gb partition I planned on using for it, but I need the other partition too. Your tutorial suggests that I need a whole hdd. Does that mean that I could lose the other partition the win10 install would be using?
Your initial question mentioned 2 individual drives.

If this is to be on the same drive as the existing Win 7....this will not work.
 
When installing on a different hard drive (not merely a different partition), win 10 gives me warning that GPT will be a problem - or some such message. I noticed that people making dual boot 7/10 tutorials use their main drive, shrink it and install win 10 there. So I tried that too, but win10 is unhappy again saying that it's MBR.
Install windows 10 in legacy mode. No need for GPT then.

Prepare windows 10 install media for legacy boot. You can do it with rufus.
 

Math Geek

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the whole drive has to be one or the other. so the second partition will take on the mbr from win 7. nothing you can do about it now. but it's not a big deal and won't effect the win 10 install

gpt is needed for drives bigger than 2 tb. so matters not to what you are doing. just install win 10 to the new partition and it will set up the multi-boot menu for you so you can chose between 7 or 10 at start-up.

but do be VERY carfeul that you install to the empty partition and notover your win 7 partition. been there done that lol :)
 
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eodeo

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Thank you for your help!

I see I wasn't clear enough. I have win7 installed on my 250gb ssd. I want to install win10 on 300gb partition of another 3tb hdd. So I do have separate drives, but the 3tb hdd has 1tb data written and I don't want to back that up just to install win10. I cannot follow the USAFRet's guide in his original reply- by having the only partition on a separate drive.

I have a separate drive for win10 , but it has data on it on another partition that I'd like not to lose.
 

USAFRet

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Thank you for your help!

I see I wasn't clear enough. I have win7 installed on my 250gb ssd. I want to install win10 on 300gb partition of another 3tb hdd. So I do have separate drives, but the 3tb hdd has 1tb data written and I don't want to back that up just to install win10. I cannot follow the USAFRet's guide in his original reply- by having the only partition on a separate drive.

I have a separate drive for win10 , but it has data on it on another partition that I'd like not to lose.
Yes, clarity helps.

So again, do this with ONLY the one drive connected.
Reconnect the Win 7 drive after.

"and I don't want to back that up"
Yeah, well......how important is this data?
 

USAFRet

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A lot more than occasional half life alyx I wanted to play on this computer. I guess I shouldn't install win10...
No, you should have a backup, no matter WHAT you're doing.

Can you manipulate the partition sizes and install Win 10 on a now empty 300GB partition?
Yes.

Can you make a tiny mistake doing it, and wipe out all the data on that drive?
Also yes.
 
I see I wasn't clear enough. I have win7 installed on my 250gb ssd. I want to install win10 on 300gb partition of another 3tb hdd. So I do have separate drives, but the 3tb hdd has 1tb data written and I don't want to back that up just to install win10. I cannot follow the USAFRet's guide in his original reply- by having the only partition on a separate drive.
Install windows 10 in legacy mode.
Boot drive (where bootloader lives) is MBR drive and windows 7 is installed in legacy mode.

If you install windows 10 in legacy mode, it can use same bootloader from windows 7.
Drive, where windows 10 will be installed, can be GPT.
Bootloader is, what matters here. That determines usable boot mode.
Windows OS partition can be on MBR or GPT drive. That doesn't matter.
 

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