It's either a screw length indicator or a pairing indicator, showing that if you remove it, there's another screw somewhere that should be removed at the same time. The HD cover should have similar marks next to its screws if it's a pairing indicator.

Seems like this is how to clean the fan, by lifting the keyboard. It seems to be the same series Vaio.

Well it's back together and 'Speccy' is showing mid 40s with a fairly quiet fan.

Yes, a lad that set out to do this job on Youtubby did remove the keyboard, but I was able to see all I needed from the bottom. A multi vane outlet had to be poked out (with soft copper wire) above and below the heat conductor rails, thus doubling the tedious task. I had no means of blowing but vac'd on the fan side while puffing into it or poking. The strange thing is how much was just inside those vanes given that I'd vac'd it in Texas. It just did not pull the dust through. I think there is a good chance that carpet of dust did move away during the flight, and flopped back as described. However, I'm braced for a sudden change and a hurried build of my Texas PC should this occur.

Average temp is reported as 45 - 48, so not as cool as I'd hoped. I'll have to put some work in to see if I can control that speed a little as described earlier.

I'll look at your link for future reference. I'd like to keep this and make it my PC replacement. My smaller Vaio is fine for lugging. Thanks again. Fingers crossed for now.

I have (second hand from my daughter) an HP laptop that did the same. Tied everything I could think of, but a bios update from HP has 'almost' completely solved it.

Long/short. Ran very very hot and was shutting itself down regularly (almost daily), fan running at stupid speeds. Has now run continuously (never turned off) for a couple of months and is cool and quiet. It has shut itself down once in that period, which was due to heat I think. So not perfect but hugely better.

Yes, it might be that even though it's fairly new - in terms of chip anyway - , operating experience might make Sony make changes to the fan settings.

I'm frustrated by not being able to get at any control to effect the change, BIOS or software. However, I have not spent that much time on it lately.

I've just noticed that although Piriform Speccy reports the overall clock speed of c 1700, the individual core reports swing between 800 and 2900 ish. Has someone set this to exceed normal limits? I note the literature says it can be turboed up to such speeds, but I never need that and still can find nothing to get into the deeper workings of the machine. Is there ever a secondary set of BIOS settings? There is a menu setting in there which implies more control, but it just does nothing when enabled.

While on that subject, again while in BIOS, the fan ran faster and oddly, the output was hotter. (This happened before I cleaned the heat exchanger.)

Does the computer run flat out during BIOS setting procedures?

Dear Rivits
 

With Reference to you comment:

"Does the computer run flat out during BIOS setting procedures? "

As one's virtual "unwanted IT Butler" - Has Sir, had a little tinkle with the RAM settings as a person known to only you and me!!!!!! - CAT III has never done such an amazing little tweak, to his recently new power supply re equipped/installed Advent intel Core II Bit Coin Miner -[My] new power supply seams to be breathing like a caged dragon.

600 W "Vital" unit - border line for the Old Girl

No the fans should be at resting rate ! - Rivets some thing is wrong !

CAT III

I haven't come across Speccy before - clever isn't it?

I'm using the aforementioned laptop at the moment. 'Tis not that old (18 months ish). My mention of one shut down was wrong. I live on a farm, and hadn't spotted that I'd had a brief power cut! Which means that the bios update has cured it completely. The intarweb is awash with people complaing about heat in the HP Pavilion G7, and I'd virtually given up on a conventional fix when I just thought a check on the HP site might be worth a last shot. (The unconventional fix was going to be a big hole in the bottom with a man-sized fan in it).

This machine is also running way above 'stock core speed' occasionally, so mebbe just an average thing?

As to the bios and fan, I wonder it it's a protection in that if you're actually in the bios there is a chance that you could start a process that makes it run hot but the bios can't do anything about the fan whilst you have it open?

Sounds logical. One is just using it and hoping at the moment. See my plaintive cry on the bad luck thread. I'll be back to pen and notebook soon.

Oh, the screw markings. Yes, I'd missed the point completely. Thanks for that.