Weird OC error
Basically i use a KVM that has USB mouse/Keyboard instead of PS/2, if i run my Opteron 165 @ 2.6Ghz or any speed much over stock the pc would refuse to boot up once it pasts post, only a blinking cursor, finally found the issue when i booted up without the KVM connected, once windows loaded i connected it and it works 100% fine. CPU/Memory is rock stable @ 35hrs prime95 and 2 days memtest. Is there any issue with Nforce 4, overclocking and USB that i missed? :)
Well, I have come across issues with KVM switches, but I always put that down to compatibility.
I have also heard of problems with USB KVM switches and Nf4, but I have never seen it myself. From what I was told, some of them just don't work because of different ways of handling USB.
The overclocking issue is weird, as you say, but you are running stuff ouside of its specification so anything can happen.
What happens when you reboot after having had the KVM switch working?
Have you checked for BIOS updates?
How long have you left it with the cursor blinking? (I am wondering if the post has really stalled, or is just taking a very long time)
Have you tried a different USB device attached at boot up (might be a USB issue?)
My guess is that somehow in the post cycle it is trying to recognise an overclocked processor and the KVM, and producing some sort of conflict/deadly embrace. Once it gets past that you can attach the KVM and it does get recognised, as there is nothing running to conflict with it.
It looks like a BIOS issue that is provoked by the overclocking to me.
maybe, but i was always under the impression that the NF4 chipset kept these things in spec, i remember i had to disable SATA 1 and 2 on my Nforce 3 Neo2 platinum when o'cin, or just not use it as it was not kept in spec and corrupted data etc.. I've left it for about 10mins and it just hangs, annoying. The KVM is crappy either way, even when not o'ced and on another rig it sometimes right clicks for no reason or the G key goes mad at times and just types GGGGG :D Tried a PS/2 KVM and its fine, only thing now is i have to use 2 sets of speakers as that USB one does audio as well, was the only reason i kept using it. This PS/2 is a 12v powered one as well and i noticed image quality went up a notch. BIOS is the latest. It almost feels like if the board is treating the KVM as a boot device when it is overclocked, weird, i have a USB stick with floppy emulation and a win98 bootdisk image, works fine when o'ced so i think the USB is in spec.
I would say that the KVM must be dodgy then, or rather at the edge of tolerances/specification. Nf4 will flatly refuse to work with some (older) KVMs. By that I mean nothing happens, the KVM is just not recognised.
What happens if you OC and have the KVM attached with no speakers?
No idea, using another KVM now :)