If eth0 is working, don't worry.
I had issues in the past with a nic not working over an interrupt, and it needed 'acpi=off' on the boot line. That's not always wise today. What is the nic?
The numbers of irqs increased as PCs progressed. The IBM XT had 8 (One 8259); The AT had 16, and there it stayed for a while(Two 8259s, one fed into the other); Then we had 24 (virtual 8259s were put into some ASIC) and interrupt sharing. Boxes often assign half-assed irqs to things, and it affects old hardware. 48 seems excessive but we could be up there.