Hi, I had a few questions regarding base clocks. While looking into buying a 7900xtx recently I noticed the boost clock is generally 2615 MHz, but the base varies. I've seen 2300, 2455, 2510 and 2525. Is this different due to manufacturers increasing it from improving the card over time or just setting that clock speed from the start of release? If the latter, are the values tested and they just decide that's a safe enough base clock speed to compete with others?

After reading on here I've seen a lot of people recommend the Sapphire Nitro+ RX 7900 XTX Vapor-X. Is this due to the base clock speed being generally higher than others?