Looks like comparing apples, oranges, and a big pineapple.
up to:
Compaq - 32-1GHz Alpha processors, 256GB memory, 224 PCI slots
HP - 8-64 way 750MHz, 4-way CPUs with 2.25MB, 128GB memory, 192 PCI slots
IBM - up to 32 ??? processors, 256GB memory, 160 PCI slots
SGI - up to 32 processors, 64GB memory (3400 series), up to 512 processors, 1TB memory (3800 series)
Sun - up to 106 900MHz processors, more than 1/2 TB memory (can't they just give the actual number?) 72 PCI slots