I finally bit the bullet and purchased a used 6,1 Mac Pro. It's the six core configuration which I picked up on Ebay. After the purchase and before shipping the seller reached out to me to make me aware of an issue with the display when utilizing the Lightningbolt connector (display through the HDMI port is said to be OK). As the unit is still covered under AppleCare they offered to have it fixed (with a 2 - 3 week delay), I could take it to Apple to have it fixed, or I could opt to cancel the purchase. Given the price I paid I think it's a good deal and decided to accept the sale on the condition Apple would repair the unit. I also requested a discount on the price in order to compensate me for my inconvenience to which they agreed. With the details worked out the unit is on the way and should be here on Wednesday. I'd like to schedule a trip to the Apple Store to have the unit repaired. However since they stated the issue was observed when connecting to the Lightningbolt connector I'm not quite sure what the issue is as there are not Lightningbolt connectors. My assumption is the seller confused Lightningbolt with Thunderbolt. I've sent them an e-mail requesting details about the issue so that I can communicate it to Apple. Due to the excitement I have about buying this system I'm filling the time by doing as much research on it as I can. So I signed up to Mac Rumors to see if the folks here can offer some possible explanations as to what may be the issue and anything I should check when the unit arrives or ask the Apple Genius to check while I am there. The seller appears to be one who buys used systems and resells them. While the auction gives the appearance of a single individual the person I have been communicating with stated he had to check with the manager on the discount. This leads me to believe it's a small company and not just a private seller. There were a number of issues in the description of the auction which required me to ask a number of questions. I'm saying this as I don't believe the seller has a lot of Mac experience and may not be doing something right in their testing. This is not to say I am dissatisfied with the seller. To the contrary they've been great to work with and have been very helpful. Just trying to offer my interpretation on their Mac knowledge. Having said all this the issue, as I know it, is there is a display issue when using an adapter with the Lightningbolt port. I've asked for specifics (such as clarification regarding Lightningbolt / Thunderbolt) and if the issue is limited to one or multiple ports. I've also requested specifics of the adapter they used to test. Being a Mac user for many, many years I've learned that sometimes a third party adapter can cause issues. When I go to test the system I assume I can used an Apple mini Display Port to DVI adapter to test? I have one for my rMBP. Of course I'll be testing using the HDMI connector too. Should I also look to test other peripherals with the Thunderbolt ports (I don't currently have any so I was going to request Apple, if possible, to that). Thanks for taking the time to read this and in advance for any advice.