Do I Need to convert my HDD partition to GPT from MBR?

Hey there, nirjhar mistry!

It means that your new motherboard can run both UEFI and Legacy BIOS.
It's not absolutely needed to convert your drive to GPT unless it's above 2 TB, that's when it is required! Otherwise the capacity above 2TB will be left unallocated.
I guess you are running either Windows 8 or Windows 8.1, and your mobo supports Win 8 Secure Boot so you might as well either convert the HDD to GPT, or change the secure boot settings to enable MBR.
However, if you decide to go through with it you should backup all the data from the drive and perform a clean install.
If Legacy BIOS is enabled when you decide to do a fresh install, the drive will be converted to MBR.
If UEFI is enabled when you do it, the HDD will be automatically converted to a GPT format.

Hope this helped!
SuperSoph_WD

So, I just found out that I installed Windows 7 under BIOS conditions. It's been happily running since around 2013 when I got the big box from newEgg with all my parts in it. When I installed the HDD I started changing BIOS parameters in an attempt to figure out if the drive was bad or my settings were incorrect. I may have changed the CSM options to boot "Legacy Op ROM first, UEFI second" or did a CMOS clear that defaulted to those options while tolling around. There's a great chance that I never set the options to boot UEFI first after the new HDD arrive and in my excitement just popped it in and installed Windows 7. The computer worked well but it wasn't exactly stable so I tried returning my CPU, GPU, and RAM clock settings and such to default which didn't help. I updated my chipset drivers next thinking that maybe an outdated driver wasn't playing nicely, but the computer still crashed a bit too frequently. Finally I flashed in the most current BIOS and that's when I discovered that I installed Windows under BIOS conditions. I know for SURE that before the flash that some UEFI thing was set to boot first, but after the flash it was gone. Also, in my Windows folder there ARE .efi files. I don't know if Windows installs them regardless, but I'm nearly positive I had this stupid computer set to load UEFI first, therefore having a UEFI mode of Windows. I could be wrong, and i usually am, but I don't know. I doubt the new BIOS would have changed the format of my drive, actually I find it nearly impossible but the ,efi files in the folder have me suspicious. I seriously doubt Windows would install .efi files if they served absolutely no purpose and couldn't be accessed by the UEFI boot.
And here's where I hope you can help. The new BIOS version is excellent; not a single crash to be had and I think that the computer actually runs a tad bit faster with it. Such a big deal was made about UEFI and since my computers last a good 6-7 years before they need replacing (and at that point it's time for a whole new system...a new GPU won't do diddly) I was like "Wow, this BIOS replacement seems awesome! I can't wait to try it out!" I suspect it's silly to be complaining over a super stable Windows installation but I feel, perhaps misguidedly so, that I'm not using ALL the capabilities o my new hardware. If you say I should get over it I will, but I just can't help but feel that I'm missing out. Firstly, is there any REAL benefit of running Windows under UEFI conditions? Secondly, if I decide to install Windows 7 in UEFI mode I figure a nice CMOS clear to reset the BIOS will be my first step. Data loss is not of any concern; after many, many years working on computers and one too many HDD fails with no back up, I've learned to store critical stuff (that includes save games too!) on flash drives or DVD's or something outside of the computer. After the BIOS is reset to defaults by force, I should then enter the BIOS on start-up and make sure that all CSM options are set to "UEFI Only" or "UEFI First, Legacy OpROM second". Once that's done I should Save & Exit, reboot, and hit F8 to open the list of bootable devices. As long as the option for the DVD drive reads "UEFI:\[Whatever]" then Windows will load up into UEFI Install mode? I tried running the Repair Options from my disc but it kept saying that the version was incompatible with the current version of Windows. I guess because NOW that I have the motherboard to load UEFI drivers first it's making the Windows DVD freak out because it's trying to locate the UEFI version of Windows and can't. Now here's my confusion. I haven't had to run OS repairs or anything since Windows XP, and even that was rare but I do remember back then that a reinstall of XP would wipe the drive clean and then install itself fresh. Does Windows 7 do that as well? I've seen mention of using Shift+10 at the install screen to bring up the command prompt and using commands delete the partitions manually. Isn't there a button at the install screen to clear the drive for a fresh installation? Is there a benefit to using the command prompt over having Windows just do it automatically? I've also seen people having trouble getting Windows 7 to install after it's been installed under the BIOS version first. Is it a simple operation that they're just botching by not really knowing what they're doing? Will the install automatically convert the former MBR drive to the new GPT drive as long as I tell it to format the drive first? Sorry for the questions...I hope you can find a short way of answering them if you have the time : )