New MB Old MB failure no Win7 boot issue (Dual Boot system Win8 fine)

Hello dear sirs,

I helped a friend replace his MB after failure, exactly same MB only new version (2 .1 not 2 - Gigabyte 970A-DS3P) He has a dual boot and Win 8.1 works fine but Win 7 doesn't. Repair doesn't resolve problem. Have looked at various fixes including Command Prompt Dir fix and Paragon software. We are concerned that re-installation will overwrite valuable files. I was wondering what you would advise, we are assuming that a re-installation will probably be needed but would appreciate some advice as to the best course of action.

Thanks ever so much in advance for any help you might be able to offer.

All the very best, May the 4th be with ...always...

 

System Model
Windows 8.1 Professional (x64) (build 9600)
Install Language: English (United States)
System Locale: English (United States)
Installed: 2/4/2015 4:22:57 AM
Boot Mode: Legacy BIOS in UEFI (Secure Boot not supported) Gigabyte Technology Co., Ltd.
Enclosure Type: Desktop
Processor a Main Circuit Board b
3.93 gigahertz AMD FX-6350 Six-Core
288 kilobyte primary memory cache
6144 kilobyte secondary memory cache
8192 kilobyte tertiary memory cache
64-bit ready
Multi-core (3 total)
Hyper-threaded (6 total) Board: Gigabyte Technology Co., Ltd. 970A-DS3P
Bus Clock: 200 megahertz
UEFI: American Megatrends Inc. FB 10/31/2014
Drives Memory Modules c,d
2500.51 Gigabytes Usable Hard Drive Capacity
1774.72 Gigabytes Hard Drive Free Space

DTSOFT Virtual CdRom Device [Optical drive]
DTSOFT Virtual CdRom Device [Optical drive]
DTSOFT Virtual CdRom Device [Optical drive]
DTSOFT Virtual CdRom Device [Optical drive]
TSSTcorp CDDVDW SH-224DB [Optical drive]

SanDisk Cruzer Blade USB Device (16.01 GB) -- drive 3, s/n 20051233900C67C09D2A
WDC WD1003FZEX-00MK2A0 [Hard drive] (1000.20 GB) -- drive 2, s/n WD-WCC3F2DY9DK4, rev 01.01A01, SMART Status: Healthy
WDC WD1003FZEX-00MK2A0 [Hard drive] (1000.20 GB) -- drive 1, s/n WD-WCC3FJZZ4LU2, rev 01.01A01, SMART Status: Healthy
WDC WD5000AAKS-00UU3A0 [Hard drive] (500.11 GB) -- drive 0, s/n WD-WCAYUJ466801, rev 01.03B01, SMART Status: Healthy 8160 Megabytes Usable Installed Memory

Slot 'Node0_Dimm0' is Empty
Slot 'Node0_Dimm1' is Empty
Slot 'Node0_Dimm2' has 4096 MB (serial number 6930D5FD)
Slot 'Node0_Dimm3' has 4096 MB (serial number 6530DBFD)
Local Drive Volumes

c: (NTFS on drive 1) * 371.06 GB 131.31 GB free
d: (NTFS on drive 1) 629.15 GB 287.43 GB free
f: (NTFS on drive 0) 500.11 GB 400.52 GB free
g: (NTFS on drive 2) 1000.20 GB 955.47 GB free

* Operating System is installed on c:

 

Was the Win 7 an OEM install or Retail install? If OEM, it's tied to the original mobo and you may be facing a clean Retail install. Consider using EasyBCD installed on the 8.1 drive to regain dual-boot.