Can I know what motherboard you are using to test the processor ? Have you tested different heatsink fan ?

Buying a set of used Motherboard + processor or separately has to be tested on the spot/or immediately after/before the deal is done coz this two is very sensitive item.

Reasons of possiblity:-

1. The seller is selling faulty mobo/processor and the buyer too busy to test so when the deadline is gonna reach, the buyer tested it not working and talk to the seller, but the seller already know that it is faulty before sold, so he refused to refund/return and blaming that the seller has fixed incorrectly/damaged the motherboard/processor. (for a S478 processor if you fix the processor incorrectly the pin still can touch in and allow you to fix it, so if you fix it not according the arrow it may burn the processor ; a mobo can be burnt in various reasons if due to improper installation)

2. The seller is using the item all the time, but in the procedure to dismentle the processor/mobo he had accidentally shot the mobo/processor without his knowing, so he pack it and ready to COD/deliver and the buyer trys to install it but fail, and contact the seller, but the seller refuse to return/refund coz he confirmed that everything is working before COD/deliver and he puts all blame to the buyer.

3. The seller is selling working item, but the buyer fix it improperly/burnt the mobo/processor and purposely call up the seller to ask for refund/return coz the buyer knows tat a limited time warranty will be given such like 1 week n so on, and for sure some seller won't refund/return coz they had tested everything fine before COD/deliver and they blame that the item is spoilt by the buyer during installation.

I dunno which one is you guys facing, in this case I think the buyer has to try for few more times again, try with different heatsink fan, dismentle the RAM from the slot and fix it back again, try with different power supply when necessary, double confirm the motherboard FSB/ratio settings and reset the bios settings, and the last check your motherboard whether can support the processor or not, if it can be supported, try to check your motherboard's Bios version to confirm whether it is up-to-date to support the processor. P/S: a 800Mhz FSB motherboard is not working with certain 400Mhz/533Mhz Processor, and it is also very sure that a 400Mhz motherboard cant support a 533Mhz/800Mhz processor. Worse come to worst, just send your processor to any computer shop to test it.

Hope this help.

Happy Chinese New Year..cheers...

Regards