The PC that works perfectly with the router - what type of onboard ethernet does it have?
Remember that if you disable autonegotiation on only one end of a connection, the other half has to drop to half-duplex. Make sure you set to 100/Full on the new PC *and* the router port at the same time.
This is definitely an issue with 82579V. My wireless connection is working flawlessly however my wired connection to same router is SLOW. I updated the latest drivers and PROset from Intel as the ones from Asus were not up-to-date. That allowed me to make a stable connection however now it is just freakishly slow. I have the adapter set to Auto-Negotiation now and everything is back to default.
I am connecting to a NetGear WNDR3300 Router. I am using a brand new Cat6 cable but my wired connection is terrible. I have read alot of people having these issues with the 82579V but I have seen no fixes besides download latest drivers and check cables. I am past the point of it being a cable or driver since cable is new and driver is up to date. Any settings and suggestions to fix this? I do not see anywhere in my router UI to change link speed so I can set them both to 100Mbs and see how it runs. If I set my adapter to 10Mbs then it will run 10Mbs however if it is on Auto Negotiation it will only run at 1Mbs and if it is on 100Mbs it will run even less that that at like 600Kbs. I don't understand this.
My wireless is running at 54Mbs... how can my wired connection be slower?
O and sorry my laptop that works fine when wired in is a RealTek RTL8101 Ethernet. And my other desktop uses some Dynex expansion PCI NIC card. They all work fine at 100Mbs speed wired to the router. Its just this new motherboard with the 82579V ethernet on board.. but I have new cables and best drivers.