I had one CPU where I turned the power on and the fan ran full blast but it did that for at least a full minute and I just gave up on that one and held the power button down until it went off. Maybe if I had let it continue to run it would have been okay... dunno.BobK wrote:I got a red LED more than once. Once it was because of a defective CPU; the other times, it was because the heat sink bolts weren't tight enough.James Steele wrote:I could try to take the lidded hexcore CPU in my 4,1 quad I converted into a 5,1 hexcore and test it in the dual cpu machine, but I'd have to worry about tightening down the heatsink too much and messing up the socket.
I just checked my notes, and in one case, tightening the bolts an additional 1/8 turn was enough to fix that. (BTW, if I recall correctly, the LEDs between the heat sinks are for RAM issues.)
Not to beat a dead horse, but the guy who runs DN computing, which sells de-lidded CPUs, said in a thread at MacRumors that it's impossible to tighten the bolts too much unless you have superhuman strength. Just make sure you do it in the order Apple recommends, and just 1/4 to 1/2 turn at a time.
I certainly tightened mine more than I expected to, but I realize that's subjective to the point of meaningless without a torque wrench reading.
(Yes, the guy at Anandtech somehow bent some pins in one of the sockets. I'm not sure what DN Computing would say about that.)
When I got the replacement processor (one of my first batch was defective), I tested it before de-lidding by installing in CPU slot A. With only one processor, my 2009 Mac Pro's fans went full blast, and a red LED went on, but it started up, and the new processor and 4 RAM sticks appeared in System Info. (There are 4 RAM slots per processor, so even if you have 8 sticks installed, only 4 will appear when there's only one CPU.)
I figured that the main risk of installing a lidded processor is overheating, because the thermal pad at the bottom of the heat sink won't fully contact the logic board; but I also figured that if you just start it up just long enough to check System Info, that shouldn't be a problem.
Also, in the 2009 MP, without a clip to secure the CPU, MAYBE it could slide around a bit if the bolts were tightened unevenly and/or too quickly, but there's very little (if any) wiggle room in the CPU socket.
I know I didn't under tighten it because I tightened it down as far as it would go, like I did with my single processor 4,1 when I upgraded it. I didn't tight it down 1/4 or 1/2 turn at a time though on each bolt, although I cant imagine with the notches in the socket, etc. that the CPU could slide around much at all, but maybe that's worth a try. I know I'll test before de-lidding next time.
Did you attach the heat sink before testing the lidded processor in CPU A slot? I know with the lid on the height is different and you COULD overtighten the heatsink.
Sigh... not sure what is going on here. I did do the firmware update, but I did it with the CPU tray in a different Mac running Mountain Lion. Doesn't seem like it should make a difference because it does show as MacPro5,1 in system info.