They are the most annoying thing ever put in a PC case. But wait... I've read that there's a new 8000 rpm Delta that pushes 51 cfm. Hang on, the math doesn't work. I think someone's pulling my chain.
The only way to revel in the sonic assault that is the Delta 38 is to buy and install one. Ah, the glory! And then you will yourself into deafness. This is a exersise in Zen discipline worthy of a Master. After about five months, your Zen training will fail you. The Delta From Hell-a will begin to waver in its rpm. Tuning the little screaming bastid out becomes impossible. As soon as you manfully accomplish this Herculean task, the fan's pitch will change. Voila, you're in heaven again.
Don't take my word for it! Travel and cooking shows on tv are agreeable, but there's nothing like being there.