If I have to re-install Windows 8 (new MB/CPU), can I retain my old settings?

I did a similar upgrade (ASRock 970 extreme3 & FX6100 to ASUS MAXIMUS VI HERO & i5-4670K), all i did was repair windows, install new hardware>plug in your USB/Disc with your win installation>go to BIOS and boot on that USB/Disc, then you'll have some different choices including install windows and repair windows, do the repair, when it's finished you should be able to boot and install your drivers.

I did the repair with windows 7, though i'm pretty sure it's the same procedure. I uninstalled some drivers before the repair or only did it after the repair.

The repair won't delete all your files on your OS disc, though it might replace the registry, not entirely sure.

And even if you have a 1440p display, i would still recommend going for a GTX970 instead, you could have the upgrade earlier because of the lower price, and it's almost as fast as a 780ti.

EDIT: Windows will ask you to reactivate it using a telephone and the product key if i remember correctly, it's because you're changing the components, and windows wants to make sure you're using a copy you actually paid for/haven't pirated or something.

1) Is your current computer from a OEM (aka Dell, Gateway, etc.) if so NO you can't do this, because the license of Windows is tied to the hardware. You would have to purchase a whole new copy of Windows and start over from scratch. As soon as Windows takes the info from the BIOS just before it displays the Windows Logo, it checks the hardware to 'talk to' so it knows how to talk right, as soon as it does, BOOM if kills Windows from preceding as it doesn't register as a 'licensed' hardware registered for that copy of Windows. There is no way to get around it AFTER you change the hardware; PRIOR to the hardware change, you could use the new license and 'reactivate' the copy of Windows under the new license, but you will have to repeat this step again when you swap the hardware, the advantage is everything is still 'in place' in Windows.

2) If you properly updates Windows 8 to Windows 8.1 through the store, then applied the Windows 8.1 Update (all required to receive patches from Microsoft) this has not changed your 'data' and use of the computer significantly. The previous editions, back to Vista when it was introduced, and added to XP, was Windows Easy Transfer, which would allow you to 'backup' your data, settings, etc. (NOT PROGRAMS THEY ALWAYS have to be manually reinstalled) to a Ext. Drive or a Network Drive, then after 'rebuilding' / starting the new PC, running WET again would 'import' everything 'magically' that even your wallpaper and icons are exactly 'as they were' (the pseudo-benchmark 90% of consumers/business believe should visual show things 'are alright" and 'nothing was lost'). As of Windows 8.1 this function was DISABLED and is NO LONGER SUPPORTED, in fact the OS will REFUSE to allow WET to backup your W8.1/8.1U !!! (shocked I was!).
Per Microsoft the 'new model' is your data should be in the normal 'folders' (Documents, Video, etc.) and all those should be backed up automatically along with all your settings as your REQUIRED to login with a Microsoft LIVE! Account to 'use' Windows 8/8.1/8.1U . Microsoft LIVE! automatically does this function (but in many cases I seen you need to still 'set' many of the directories) AND you get like 1-10GB (I forgot what the amount it is) for FREE. If you need more you need to pay more of course, BUT when you 'Move or reinstall Windows 8.1Upate" it will "automatically and effortlessly restore all your settings, data, etc. as it was synched under the SAME Microsoft LIVE! account you just logged in with". This is the ONLY WAY (per Microsoft) to backup all the settings, data, etc.

3) NEVER will the 'Registry' be backed up nor restorable, this is intertwined with HAL which determines alot of how the OS works, which if backup able would be a easy way to circumvent alot of licensing and authentication processes software (not just Microsoft) relies on. ANY Program all needs to be reinstalled all over again, BUT the "settings for all my software and games" is now housed under your 'profile' (a main reason for all those folders under 'My Documents' for all the games, software, etc.).

4) Steam games have a 'trick' you can perform, to 'migrate from one HD to another' (Google Steam Games move to new drive) to avoid all the download time of those games, though each one will need to be 'reinstalled' so it sets the registry, etc. with all the proper settings.

5) NO you can NOT "simply copy some folders to the new installations", it has NOT worked like that since VISTA was released. FORGET ANY OLD XP TRICKS (everyone has to) they all do NOT work and only 'break' things, because the OSes are significantly different since new security model, etc. was installed with Vista going forward. The 'parts' that make things work are in MANY MANY MANY different directories BASED ON EACH PROGRAM SEPERATELY. So there is no 'drag AppDATA' and be done, because that ignores the one key file from "C:\Windows\System32\AE3FTS30-ASYDGHS-7253\blah\yada\echo" that is a hidden system directory only accessible by 'Trusted Installer' (Google this inaccessible system 'account' built into Windows that make you no longer 'God' over your Windows).

For the gpu, the best option is always the best price/performance, right now the 980's price is good compared to the 700-series, though it's getting blown out the water by the much cheaper 970 with similar performance. Cheaper means you'll be able to upgrade sooner, which is good because not either of the two will be great cards in 3-4 years. So being able to upgrade in 2-3 years because you didn't spend as much now is a better solution.

So yeah right now you'll have less performance, but in 2-3 years you would have been stuck with the 980 whereas you'll be able to get a new card at that time if you didn't spend as much and bought the 970.

Pretty hard to explain but i hope you understand what i mean. Best price/performance is what will give you the best performance over the years between upgrades, for the same budget.

The main element here is your licensed version of Windows was correct, as many get a OEM 'on sale' or 'parents got me' and then are not capable of playing at the level they want to achieve and figure 'if I just change out the CPU/Mobo all will be okay' and not realizing there is alot more to it.

You did every step right (had a bootable USB with w8 at hand) preparing for the worst but glad for the easiest Most dont' even think about stuff like this, then when it does 'fail' they 'reboot it to fix it' over and over, blah blah Oh F! My system is piece of S! HELP! and so on. Nice to see someone finally doing it right and getting the best results. Enjoy the new system!