# Cannot overclock or boot in AHCI or RAID mode



## holdenms (Feb 23, 2016)

Hello,

I've been having this problem for the past week. Let me start off with my specs:

CPU: Intel i5-2500k CPU @ 3.30GHz 
GPU: NVIDIA GeFore GTX 570 
Motherboard: Gigabye Z68X-UD3H-B3 
RAM: 8GB 
Power Supply: 850W 
Hard Drive 1: INTEL SSDA2CW120G3 ATA 
Hard Drive 2: ST31000524AS ATA

So, before I installed Windows 10, like back in August, I was able to overclock through EasyTune 6 and BIOS no problem. After I installed Windows 10, I didn't even try overclocking until recently. I first tried through EasyTune 6, which just caused my PC to restart before it reached the Windows screen. So I reset my BIOS, and then tried to overclock through the BIOS. Sometimes the computer would reboot right before the Windows screen, and other times I would get the "inaccessible_boot_device" blue screen of death error. Two times I got an error about the settings being too high for an overclock (which is not true, I was always able to do it at those levels).

I have tried updating the BIOS and installing all drivers, but there's a problem, almost none are supported by Windows 10, so I have no idea if they are being installed correctly. I even did a clean wipe of my computer and reinstalled Windows 10, but still no luck.

In addition to this, even without overclocking, I cannot set SATA drives to AHCI or RAID mode. It will only boot in IDE. Before I wiped my system and did a clean install, I was getting the inaccessible_boot_device error. After I reinstalled windows, it just stays at the "loading operating system" black screen.

If I restore BIOS to default settings, my computer boots fine. Also sometimes I attempt just to turn up the Frequency to x45, and leave the voltages on auto, and the computer will boot, but when I return to BIOS on another restart, its back at x33, so the increase is not saving.

I have attempted the registry edit hack, but I cannot find the proper files anywhere. I am at a loss for what to do. Will reverting to Windows 7 fix this problem? And if so, how do I do that? This is really bothering me, because with an overclock I should be able to play a lot of new games on relatively high graphics settings, but I can't because I can't overclock. Sorry for the long post but I have tried literally everything I can think of!


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## JimE (Apr 16, 2009)

Unless I'm mistaken, AHCI needs to be set before the OS is installed. 

OCing can change over time as the hardware ages. So what works one day, may not work weeks/months/years later. Just something to keep in mind.

The OS shouldn't affect changes being made in the BIOS, so at least part of the problem would appear to be motherboard/BIOS related.


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