My friend has offered me a PC he has had kicking around his loft for a couple of months (he often does weird deals with people and ends up with piles of hardware). It is a 3Ghz processor and boots perfectly from cold. Switch it off and you have to completely unplug it otherwise it fails to reboot. It also drops .5Ghz on reboot. Anyone heard of this weird oddity before? I am potentially interested in buying it cheap for my daughter as she is currently on 1.4Ghz and needs an upgrade. This is a bizarre issue I have never come across before, any ideas folks? Oh, the processor is NOT at fault as it works perfectly and allows reboot at correct speed when inserted into another PC. Is this as simple as a faulty motherboard, if so why does it reboot perfectly from cold and show up issues unless you completely unplug it. How can a motherboard influence the loss of CPU?
My first thought would be to replace the CMOS battery. It's not normal "dead battery" behaviour, but it's about the only thing outside of a dodgy board that makes sense given the description. When you say it "doesn't reboot" and then you say it "drops .5GHz on reboot"... is it not booting Windows? More details!
Do you mean that there is an actual performance loss of 500Mhz upon reboot without unplugging the system? Perhaps there is something that is imposing an over/underclock and when the system is reset it maintains the new settings until it is unplugged, due to a bad CMOS battery. What model processor is it and is there any odd third party OC software floating around on it? *edit Although this is highly unlikely, is it possible that something is pulling power away from the processor and lowering the voltage causing a performance drop. Not quite standard behavior either, but it's just a guess.
Replace the case. I've had the problem where you have to unplug the system after turning off the system and it was only fixed by changing the case. Perhaps there is something wrong with the power supply or something is shorting out on the case. Try it anyway. No idea on the lower clock. Is it an Intel chip with speed step?
Hello and thanks for the replies. I am going to have to wait until my mate brings the PC round to mine in order to check / ask these questions as I have yet to use it. He seems keen to sell it on for a very low price, which rings alarm bells. I thought it was worth asking in advance so that I can test your potential solutions on the day <after he's named a price of course lol> I'll be back in contact once I've seen it for myself. Thanks!
Well if the CPU works fine then it's a mobo issue. If its a P4 775, get a C2D compatible motherboard, pop all everything in that, and when the time comes for an upgrade, you can use the Core 2 range, which is damn good. Before you dish out, check for BIOS updates, and stress test the system (run Prim95) to check if it's stable. Also look for errors and messages on boot. Is there more than one beep?
Definately sounds like a motherboard issue. Reset the BIOS to optimal defaults. Also check the temperatures and voltage settings. Voltage can be out by a 10% tolerance (e.g. +12V should be at least +10.8V). If he's el cheapo PSU, you might want to think about replacing it. Think about using a (semi-)decent 400W PSU, maybe higher if you have lots of peripherals / devices. Does the chip definately run stable on a different board? It could be a B-grade chip. Often, the chips are in fact identical, only the "premium" ones get set to a higher clock speed. It could be that the wrong chip fell in the wrong pile, maybe? It is a long shot, but there's a remote possibility there!!! Your easiest solution would be to try changing the board. What socket is it? Go for a brand you trust - I would personally recommend ASUS. You should pick up one of their entry-level boards for around 40 quid.
