Lga1150 and prior (lga1155, 1156, 1366, 2011, 2011-3, some 775 etc) all use DDR3 ram. It's only the newest gen like lga1151 that uses DDR4. Totally different ram, speeds, pin count. You can't physically use different DDR. So whatever ram you do have for that i7 is what you'll use for the new mobo. To get best performance from Windows, games, most apps, you'll want at least 8Gb (2x4Gb) of 1600MHz. Depending on the mobo, you can change that up for more and faster, most Z boards can use 32Gb or 64Gb of upto 3200GHz. Mainly 16Gb (2x8Gb) bought in 1 package of 2400MHz is considered good, higher than that might be problematic since your cpu doesn't OC.