Beeping on a cold startup

Hi Folks,

I hope that you can help me.
My computer has developed a habit, which seems to only happen during the colder weather - despite central heating - of beeping at the first start up of the day.

Now I know that normally the basic advice would be - count beeps and check against BIOS manufacturer. Problem is I don't always get the same number of beeps - normally it's between 4 and 7, this morning it was more like 20.

When it started, I thought that it may be a memory problem, as we had recently added 8Gb of extra RAM, but it follows the odd pattern above. I have lots of theories, but I cannot understand what would cause it to be so weather specific.

I'm running a Cyberpower PC, Asus P7P55-M Mobo, i5 760 Overclocked to 3.49Ghz, Sealed Liquid Cooling system, Intel SSD and Samsung 1TB Hard Drives. Plus some external drives, which are not always powered on at start up.

EDIT: Forgot to say, other than the beeps, it starts up fine, everything boots okay, just beeps a lot and seems a bit slow.

Any thoughts appreciated.