I have a Toshiba Encore 8 basically the same as yours. I have been running full speed 24/7 for 6 months. Mine doesn't really get warm and it only cost £100 so I wasn't too bothered if it had problems. My battery charge is still the same and I use a SD card for Boinc. At night I leave it on a metal laptop cooling stand. I find that leaving things like this on a cold surface like metal or glass etc seems to help better than good airflow. Most of the components in things like this are usually protected from getting too hot. The fact that it is running using turbo is a good sign.

If you have access to a table fan of something like that (external USB powered far etc) you could point the airflow from it so that it passes the backside of the tablet. This works well for my phone to keep temps down when I am not using it but only crunching.

Alternatively, if your computer case has a fan in the top and you place it on top like you write it would also help, I make use of the top fan in my pc chassis like that. :-)

When it comes to batteries, they usually don't like to be charged to 100%, because crystallization begins when pushing those last 20% in from 80% to 100% (This is why a Prius won't let you fully charge the hybrid battery, because if it doesn't then it can charge and discharge a lot more than a thousand times.

Sure, glad to help!
On the battery side of things; remember to perform a full discharge-charge cycle once every couple of months though, because that will recondition the battery so that it won't develop any memory effects.

Happy crunching!

They're in my e-bike, in my tablet, in many other rechargeable battery powered apparatus here and the word is...

"Li Ion batteries don't have the kind of memory effect that NiCd batteries have, so they can't be reconditioned.

Some Li Ion battery packs (e.g. laptop batteries) have a little circuit that keeps track of the capacity of the battery. Occasionally, this sensor can get thrown off-track by repeated shallow discharge and recharge cycles. If so, you can recalibrate the sensor by letting the battery discharge fully (to the discharge cut off - put that screw driver down!!). This doesn't actually do anything beneficial for the battery itself, it just resets the little monitoring circuit.

Plenty of info to be found by Googling "reconditioning Lithium Ion Batteries"..."

and by the same guy later on...

"Li ion batteries are *very* finicky about charge & discharge parameters! To quote Wikipedia (emphasis mine):

A stand-alone Li-ion cell must never be discharged below a certain voltage to avoid irreversible damage. Therefore all Li-ion battery systems are equipped with a circuit that shuts down the system when the battery is discharged below the predefined threshold. ... This is also one of the reasons Li-ion cells are rarely sold as such to consumers, but only as finished batteries designed to fit a particular system. ... Short-circuiting a Li-ion battery can cause it to ignite or explode, and as such, any attempt to open or modify a Li-ion battery's casing or circuitry is dangerous. Li-ion batteries contain safety devices that protect the cells inside from abuse, and, if damaged, can cause the battery to ignite or explode."

Or as the guy who really knows about them "Li-Ion batteries loose storage capacity over time, to include keeping them on a store shelf at the rate of about 20% per annum. They parish eventually."

My 4 core tablet trundles along at 1512 with 2 cores crunching, seems to alternate between that and one step lower on 3 [1026] and more or less sits on a lower frequency when on 4, which is when the charger is hardly able to keep up unless screen switched off. Throttling is I suppose as much regulated by temps as they or stepped down on modern desktop processors. Monitored with CPU-Z v.1.10 from play store. The battery displays as being at 25.0C [well below the 35C cut-off set in BOINC], thermal sensors all going 60-78C... sitting front of a USB fan at an angle of 30 degrees to the front.