Yes, this is known as the "double boot issue". I have experienced it in the past going way back, as do many others, and there are lots of threads on other forums about this. Many "fixes" are offered that seem to stop it, like a dif bios - earlier or later, a dif power supply, the "hot swap" fix, manually entering ALL mem parameters, not using GSKill, the "APM" fix, the Iastor LPM fix, using only MS drivers, etc. endlessy. But I see it in another light. All the double boot fixes MAY work for peeps who do NOT use the mobo Artificial intelligence. They have done a manual O/C and one or two settings they made just dont cut it.
No problem double posting must not be confused with instablitity related reboots and BSOD and freezes.
The PREVIOUS solution to the double post is to set Spread Spectrum to enabled - not auto or disabled. If it makes the double boot go away, that means you are in an environment that is EMI heavy - like a 25" cellphone tower that is a block away. Or in an office with flourescent lights. If you are on a farm in Nebraska, prob not your answer. I distinctly remember my P965 Gigabyte would
triple boot if I changed a bios setting, twice for spread spectrum off and another for the bios change.
There are three ways to auto overclock this mobo.
1.)The TPU switch (no changes allowed)
2.)The Turbo mode in EZ page
3.) Auto Tune in AI Suite (Windows - various levels)
When using any of these modes, you MAY get the Double boot, especially in Auto Tune higher levels.
The double post (cold boot, then warm boot) when MANUALLY overclocking means something is a bit too far out of a workable situation. This is what makes for instability - freezes and sporadic reboots and BSOD's. One of the most important is the CPU + overvoltage setting. I think also that ASUS worked very hard to have their boards get big overclocks, which is good for overclocking (and marketing), but many of the parameters are at the ragged edge, especially as you push things higher. You really have to know each and every bios setting and how it interacts with each other. I personally think there are TOO many bios settings.
HOWEVER>
auto overclocking usually works stable 100%, but brings in the double post with no spread spectrum. For example, when I set the display color parameters on my ATI vidcard control center (brightness, gamma, contrast etc.) for my LCD, as I boot into Windows, the desktop appears, then the color mix changes to my settings - it doesnt happen instantly, it flickers to the
custom setting at a certain point. This is how i see the double post. The bios booting normal, digesting the Artificial intelligence and booting into it - in AUTO O/C mode. I do not see it as an "issue". I interpet it as normal operation.that does no harm whatsoever. Doesnt bother me a bit. You can stop it in manual mode, but you better have weeks of research on the web, so you understand what works and what doesnt.
UPDATE:
Heres yet another "fix" posted
I have the double boot problem fixed. I updated to BIOS 1505 and pressed the CMOS reset button in the back of the motherboard for five seconds. I had to re-enter all my BIOS settings but the double boot is gone! I'ts so much nicer.
I have both the 1505 and 1506 transition bios, but am a bit nervous about installing them. would be great if it truly solved double post, however it does not seem the poster is using auto-overclocking
Question: Did 1505 bios make spread spectrum "auto" as enabled?