Quick question. I have been mining Monero since Jan. I have several PCs with GPUs.

So I have a Dell 5600 with 2 RX5600s. Here are the results from it from supportXMR
HR = 1.18 KH/s
1 HR avg = 1.05 KH/s
24 HR avg = 1.22 KH/s
Total = 3,216,958,344

I have another similar PC with 2 GX950s:
HR = 1.09 KH/s
1 HR avg = 813 H/s
24 HR avg = 831 H/s
Total = 12,769,325,933

So, these have been mining for very close to the same amount of time. Why are the totals so different? Is there anything I should check?

I am using xmr-stak 2.4.2 on both.

I have a third that I put online much later (like months) and it has already passed the 5600 on total mined. It is about 1/2 the hashrate.