Laptop coolers are a mixed bag. Having an active laptop cooler (with a fan) will always produce better thermals than with nothing (how much better depends on the cooler and the laptop), but it also adds additional fan noise (might balance out if your laptop's fan doesn't have to spin up as much). I've always kept my laptop cooler fans running pretty low RPMs so they are barely audible. I only buy laptop coolers with adjustable speed fans.
But let's face reality, laptop coolers aren't very portable. You'll probably leave a laptop cooler on a desk 99% of it's lifetime, and you'll only ever use it when you're using your laptop at that same desk.
In college, I had an HP laptop whose hdd was thermall unshielded, making the palmrest noticeably warm. I had a sweaty left wrist many times until I set it on a Zalman laptop cooler.
After that, no more sweaty wrists, and CPU fan rarely spun up.
Right now, my work laptop is on a CM Notepal Ergo
to raise it to my 2nd monitor height. I just ran a Prime95 test (CPU stress test) for you.Fan on:
CPU = 91C max
hdd = 31C
GPU = 71C max
spent a lot of time at 3.2GHz (that's max turbo with all cores loaded IIRC)
Very similar/same results with fan at max RPMFan off:
CPU = 94C max
hdd = 31C
GPU = 74C max
CPU spent most of the time around 3GHz (throttling)
Main: i5-3570K, ASRock Z77 Pro4-M, Asus GTX660 TOP, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Hand-Built Wood Case