Boot Disk Issues When Overclocking

[JamesD]

Right this is weird. I have an Abit ICG-7 Mobo with Phoenix BIOS. The motherboard comes with SoftMenu in the BIOS where the overclocking takes place. It's simple to use, but when I increase the CPU Clock and save setting and exit, when it boots up it starts booting from CD-Rom and asks for the Boot Disk Any suggestions? All help appreciated

[marc_ellis]

What speed are you setting the FSB to?

[JamesD]

First I tried 215 and then 210. I know it's got be multiples or something but I'm new to overclocking so maybe you can help. (it had the sample problem on both speeds btw).

[Agent]

Maybe your HS cant take the high FSB (is it locked ?), and its stoping the HD from being seen, and trying to boot from other devices.
Does your HD show at POST ?

[marc_ellis]

OK fix your AGP and PCI slots to 66 and 33mhz. then try 215 FSB again.

[JamesD]

Nice one marc_ellis thanks alot. It works now but could you explain what was going wrong please just so i know hehe thanks. and also seeing as ive fixed the AGP and PCI slots, will it cause any problems? Thanks again!

[marc_ellis]

By overclocking without locking up your AGP and PCI slots you are overclocking your video card, sound card and other stuff. These don’t like being run out of sync. So by locking your AGP and PCI it allows you in increase your FSB without overclocking your cards. It won’t have any effect on your system by locking them up.

[eldren]

Your motherboard runs on a base frequency called the FSB (These days, 200MHz FSB is standard). Your CPU obtains its frequency by multiplying the FSB by what's called a multiplier. For example, to get 2GHz, at 200MHz FSB, set the multiplier to 10x. The PCI bus and AGP bus also derive their speeds from the FSB, if they are not locked. This means that, as you raise the FSB, they are taken further and further away from their default speeds of 33MHz and 66MHz, respectively. Obviously, card manufacturers keep to the standard speeds, so as you overclock the two busses, some cards may stop working. As IDE works off the PCI bus, harddrives also go wonky when the bus is too far out of spec. Locking the busses solves this.

Lastly, the RAM. RAM can be run synchronously to the FSB, or asynchronously. When run synchronously, the RAM's speed is twice that of the FSB. Otherwise, it at a percentage of the FSB. For example, in my motherboard's BIOS, I can set the RAM to run at 83% of my 200MHz FSB, meaning that it'd run at 166MHz. Most people will tell you that having your RAM run synchronously will improve performance. However, this is where things get a bit iffy, with RAM timings and all. There are usually four settings - Tras, Trcd, Trp and CAS. All of these represent delays in terms of clock cycles. In short, the lower these numbers, the better. The lowest practical values most people use are 5-2-2-2, respectively. However, your RAM may not be able to attain such speeds. The RAM specs in my signature is an example of this. Setting your RAM timings too low may result in your system being unbootable, meaning you'd have to reset the BIOS to fix it. Don't try changing your timings if you're not comfortable doing this.

Hmm, unexpectedly spammy.

Edit: Go figure, my sig isn't working. :/ My RAM is at about 7-3-2-2