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fersy

macrumors newbie
Original poster
May 20, 2020
24
4
Ok i have mac pro 4,1 flashed to 5,1. I tried to install windows using bootcamp with windows dvd. When the mac restarted it went to the black screen with flashing cursor. I realised i was suppost to hold option key at boot and select the media but i decided i didnt want to install windows after all so i went into the boot menu and booted into high sierra. All seemed fine except i now had a 100gb partition on my hdd reserved for the windows i wasnt gonna install so i attempted to delete it and turn it all into 1 partition again in disk utilty using the partition pie thing. Anyway i thought all went well but when i tried to restart my mac its giving the chime, then the white screen then going back to the black screen with the flashing dos prompt cursor. I can no longer even get into the boot menu or the recovery or even perform operations like resetting the pvram. I basically cant do anything with it at all. Has anyone any idea what i have done and if i have any options to get back into it? Any help would be greatly appreciated as ive been at this for hours and im lost now tbh
 

h9826790

macrumors P6
Apr 3, 2014
15,199
7,517
Hong Kong
If you completely screwed your primary boot drive, you will need another boot drive / bootable installer to recover from the current situation.
 
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startergo

macrumors 68040
Sep 20, 2018
3,446
1,485
Ok i have mac pro 4,1 flashed to 5,1. I tried to install windows using bootcamp with windows dvd. When the mac restarted it went to the black screen with flashing cursor. I realised i was suppost to hold option key at boot and select the media but i decided i didnt want to install windows after all so i went into the boot menu and booted into high sierra. All seemed fine except i now had a 100gb partition on my hdd reserved for the windows i wasnt gonna install so i attempted to delete it and turn it all into 1 partition again in disk utilty using the partition pie thing. Anyway i thought all went well but when i tried to restart my mac its giving the chime, then the white screen then going back to the black screen with the flashing dos prompt cursor. I can no longer even get into the boot menu or the recovery or even perform operations like resetting the pvram. I basically cant do anything with it at all. Has anyone any idea what i have done and if i have any options to get back into it? Any help would be greatly appreciated as ive been at this for hours and im lost now tbh
Disk utility sadly sometimes corrupts the partition table if you delete Windows BOOTCAMP partition. There is a way to recover it, but you probably have to boot in Recovery Mode or from external installer. You can try live Linux USB/DVD and gdisk to view the partition info:
Semi-Automated Recovery

When GPT fdisk starts, it attempts to read the various GPT data structures. In doing so, the program checks the CRC values stored in the main and backup headers, and it performs various other sanity checks. If GPT fdisk detects a problem, it will notify you, and if a fix is obvious, it will implement it automatically. For instance, consider what happens when GPT fdisk discovers that the main partition table's CRC doesn't match that stored in the main header:

Repairing partition using hexdump of the boot sector:

Repair GPT partition from Recovery:

 
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fersy

macrumors newbie
Original poster
May 20, 2020
24
4
Cheers for the replies guys ill have a read theough all those links when i get back from work. Heres the thing tho even if the hard drive was screwed and couldnt boot shouldnt i at least have been able to do things like get into the boot menu by holding the alt key or the recovery menu by holding cmd r? Surely they happen before it boots the hard drive in the same way for example a windows pc has safe mode and boot menus coded into the motheboard bios? Say for example my hard drive failed and i lost everything surely there would still have to be a way to access those menus to enable you to install osx on a brand new hard drive to get the computer up and running again? Im not that bother if i lose what was on the hdd as most of my stuf is backed to other internal hard drives so refromatting and reinstalling wouldnt bother me but without being able to access the recovery menus etc i dunno how id be doing that lol. Ive 20 years experience on pc and thinks like this are a breeze but only 1 on mac and im a bit confused how these things seem to work lol
 
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startergo

macrumors 68040
Sep 20, 2018
3,446
1,485
shouldnt i at least have been able to do things like get into the boot menu by holding the alt key or the recovery menu by holding cmd r?
Only if the disk structure is intact. If the geometry is screwed up but you did not delete your HFS+ or APFS partition there is still a chance to recover it. Try getting in the recovery first and in terminal:
Code:
diskutil list


sudo fdisk /dev/diskX
#Make a screeenshot
sudo gpt -r show diskX
#Make a screenshot
 
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fersy

macrumors newbie
Original poster
May 20, 2020
24
4
But how could i do that if i cant get into recovery? None of the boot key combinations work. Thats what confusing me because, say for example i say screw it ill do a fresh reinstall. Ive loads of spare harddrives and a macbook where i can obtain the os again how could i put in a new hard drive and install a fresh os if i cant access any menus or options to allow me to select the new os to boot from. Surely there has to be some sort of basic os coded into the motherboard to allow you to be able to do anything. What i mean is the mac doesnt just know what harddrive its booting from everytime you start it. Theres a bootcode or something in there that tells it. Which is pre hdd and pre osx. Maybe theres something i can clear like you could move a jumper or remove the battery to clear the cmos on a pc? As i said im not bothered about saving the os on that drive im happy to swap hard drives and start from scratch but surely there has to be a way to do it. Also thanks again
 
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orytek

macrumors member
Jan 20, 2008
30
11
This happened to me when I tried to install BootCamp on my Mac Pro 4.1-> 5.1. I tried to do a workaround install since Bootcamp Assistant doesn't support older Mac Pros. My Mac Pro would immediately do a flashing cursor at re-start. No key combination had any effect.
I removed all the disks except a backup MacOS drive and restarted about 3 or 4 times until something cleared up and it booted.
 
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fersy

macrumors newbie
Original poster
May 20, 2020
24
4
Ok cheers guys ill go try all those things now. I was at it till 8.30 am this morning then ive been in work all day so this is the first chance ive had. Hope im not up to 8.30 am again cos im back in work at 3 lol. Im thinking even if i stuck a spare hdd in it and could install the os to that and make it bootable i could maybe put the screwed up ssd in, try and pull what files i want off it, reformat it and then clone the new boot disc back onto the ssd. I was thinking about a fresh install for a while anyway as i bought the mac from a friend and it still has his name in it instead of mine but i didnt want to have to reinstall all my logic plugins again lol
 
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orytek

macrumors member
Jan 20, 2008
30
11
Main thing is to save your Mac. I was really sweating bullets when my Mac Pro was virtually bricked, so after removing the drives I was pretty happy to see the apple logo on the 4th re-start
 
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fersy

macrumors newbie
Original poster
May 20, 2020
24
4
Ok guys, thanks for all the help. I was able to use my macbook to download high sierra and create a bootable usb and get it all up and running with a fresh install on a spare drive. I then put my ssd that i had originally been booting from im and was able to get all my files off it. I could probably have save that install as everything was there it probably just needed the partitions fixed but i fancied a clean install anyway so i wiped it and then cloned the new install from the spare drive to that, reset the pvram as it was booting slowly and it was flying again. Then i put in my new rx580 graphics card and nothing lol. Doesnt appear to be doing anything at all so ive been doing a lot of reading and failing that ill do a new post in the right place but at least the mac is up and running again so thanks
 
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MIKX

macrumors 68000
Dec 16, 2004
1,800
670
Aussie in Japan
Did you do this ( shut down first ) ?
NVRAM_PRAM_ResetMac.jpg

Read small text in the pic.
 
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fersy

macrumors newbie
Original poster
May 20, 2020
24
4
Did you do this ( shut down first ) ?
View attachment 918329
Read small text in the pic.
Do you mean for the graphics card issue m8? If so yeah loads of times but it never seems to work or do anything. When i do it with the stock card in the mac restarts and i know it worked thats how i did it last night when my cloned drive was booting slowly but it doesnt seem to work with this new card in
 
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