KP on startup after a long time

[wavesequence]

I'm writing hoping someone will shade some light about this issue I'm facing.
My hardware is made up of X58a-UD3R, HD 5770, 12GB of RAM and a simple 1TB Western Digital HD running, until few months ago, Snow Leopard. The computer itself runs also Windows 10 on a separate HD, which is always off when Snow Leopard is running - and viceversa.
In other words, I must select the operating system to load and push an external switch to power the designated HD.
I did an attempt to load the operating system but I obtained several KP. Thus I tried to load iBoot 2.7 nad got the same KP.
What gives?
Is there a way to boot the PC and doing and attempt to repair the operating system on the HD?.
Thanks in advance.

 

[Nodarkthings]

Did you try booting in Safe mode?

 

[wavesequence]

Did you try booting in Safe mode?

Thanks for your reply... In the meantime I burnt a new CD with iBoot latest version (3.x) but the results are always the same. I mean that using iBoot I still get a KP. At present, I don't know how to boot in safe mode, neither from iBoot nor from the HD.

 

[Nodarkthings]

I never used iBoot but I suppose that if you have a KP with it, the issue is elsewhere.
Does it boot on your Windows drive?
• If not, I'd check every connector inside, unplug/replug the memory sticks (if you have 2 of them, try to boot with only one, then only with the other), try booting without anything external connected.
• If it does boot on your Windows drive, then I'd check the BIOS settings, it might be that you've lost some important settings — very likely to be your old CMOS battery that needs changing on such an old pc.
EDIT: well, my second point applies in both cases, in the end...

 

[wavesequence]

I never used iBoot but I suppose that if you have a KP with it, the issue is elsewhere.
Does it boot on your Windows drive?
• If not, I'd check every connector inside, unplug/replug the memory sticks (if you have 2 of them, try to boot with only one, then only with the other), try booting without anything external connected.
• If it does boot on your Windows drive, then I'd check the BIOS settings, it might be that you've lost some important settings — very likely to be your old CMOS battery that needs changing on such an old pc.

Very kind of yours... Well, My PC has a sort of switches that can let me decide what will be the HD that boot. Thus if I select the switch connected woth Windows 10 OS, it will boot under Windows 10 and in the meantime Snow Leopard HD is turned off. Just this evening I reloaded BIOS settings, checked if something was missing but - apparently - it was everything OK. What lets me quite doubtful is that nothing has really changed since a long time. I just powered the HD where Snow Leopard resides, attempted to boot with it, but got a KP. Same said for iBoot 3.x.
I need to check if something has gone wrong somewhere else.... tomorrow... here in Italy it's midnight... time to sleep