Wouldn't sending chips to you attract importation charges when they were sent back
Yes, don't ship them from the UK to the US, then have them shipped back, you'd get charged all over for the fees!
You could order them from a US seller, have them shipped to someone here, then have them shipped to the UK, you'd pay import taxes once.
I am not aware of anyone in the UK that delids these processors, but if you can source the CPUs there it may be worth checking if someone does it, or maybe someone familiar with installing the lidded CPUs can just do the entire upgrade for you, which would eliminate the risk (some small computer shops will do this, and depending on the shop, they should warranty their work, and if they break your board doing the upgrade, they should cover it)
Delidding the CPUs is not difficult, but certainly not risk free, especially since these are soldered to the IHS. I would very strongly suggest you not to delid a single set for yourself, the risks of damage would be far greater than just installing lidded CPUs. If you don't have another machine to test with (A Single CPU, or 5,1 Mac Pro, or just a PC that can run this CPU), testing the CPU before delidding would require you to install the CPUs lidded anyways, and without testing it, if the CPU was bad before you delidded it, you'd be out any possibility of returning it after you modified it like that.
With the first 4,1 I got I wanted to upgrade the processors, but with so many guides with conflicting information, I was far too nervous to do the lidded CPUs, as the CPU boards were very expensive at the time (still are), and noone else was selling delidded CPUs at the time, so there really wasn't an option I was comfortable with. I was fortunate that I work on and sell computers for a living, and I have a lot of older cpus around, practiced delidding many cpus with various methods until confident enough to try on a cheaper xeon quad core, and after that worked, finally the X5690 that's in it today. I've never actually done an install with the lidded CPU, it still scares me to take the risk, so I'm certainly biased towards the delidded. The only problems I've run into with customers damaging things with the delidded CPUs, was caused by putting the CPUs in backwards, so I don't feel there is much risk. I am not the best person to ask about the actual risks with installing the lidded, but as I understand, over tightening is the big one. I think properly sized washers could reduce this risk.
My suggestion is to figure out what you'd pay for the CPUs you want in the UK. Probably assume an extra $10-$15 for the tools you need (the screwdriver is easy to find, you usually need to buy a small set, but most hardware stores have it in a kit for around $5. You'd want to find some thermal paste, which should also be $5 or less at many computer stores, and the thermal pad) Compare that to what you'd pay for the delidded CPUs, and decide if the reduced risk is worth the extra cost. Since you're already spending time researching how to do the lidded upgraded, the time researching what you need to do isn't really a factor, actually performing the upgrade with the lidded CPUs should only take a little bit longer (you have to cut the connector, cut and add thermal pads, and possibly remove the tray and retighten in a few times while you get it right.
The end results are the same. I have gotten some boards from customers who have attempted the lidded upgrade, the boards come with all kinds of bent pins, but so far, we've been able to repair all of them, so I think even if you do over tighten a little, it probably can be fixed (If this happens, I would suggest you stop pull the CPUs, take some pictures and get some advice before attempting to rebend the pins back, they are very fragile and bending too much will cause them to break off, which would require finding someone to replace the entire socket or living with a bad ram slot or whatever those pins controlled. With many pins being redundant, even a few broken pins doesn't mean it won't work.[/user]
