2 
1 No Bootup with T9500 CPU
Hi
Hoping to upgrade my mid-2007 24” iMac to a ‘Penryn’ CPU, I very carefully read/absorbed lots of detail descriptions/accounts of how/why/what not to do, followed them meticulously and fitted a (allegedly) new T9500 CPU.
All back together, I plugged in and tried the start button.
Nothing - apart from the usual two quick buzzes from the optical drive. Took the ‘glass’ and the alloy frame back off, tried again and the same result plus noted very small flick of the CPU fan. Numbers 1, 2 and 3 of the LEDs to the right of the memory slots come on but nothing else happens, no chimes, no screen illumination, nada! - and I waited 15 minutes in hope.
Put the old CPU back in and away it goes, as reliable as ever.
Fearing I’d missed something I’ve done the same exercise three times now, all with the exact same result. I now KNOW I’ve not messed up because as soon as I put the old CPU back in, Bingo! away it goes, perfect boot, everything. I’m writing this on it.
There are lots of articles about how to do it, none mention any problems booting afterwards. There are only two posts that say the T9500/T9300 might be incompatible amongst the very many that say they are perfectly OK, other than speed reporting errors. The two I’ve found saying the CPUs are incompatible are effectively disputed in the following posts.
To be candid I really don’t care if the speeds are reporting incorrectly, all I need is SSE 4.2, which the T9500/9300 have and that will allow me to install Catalina with a patch.
Bottom line: Have I probably got, as I suspect, a faulty CPU, or is there somewhere some definitive information that says the T9500/T9300 are NOT compatible - and that incompatibility something is more than just the misreporting of speeds.
Will
Update (06/18/2020)
OK, I understand the concept of the EFI not being able to use the T9500/T9300. That said, I have never (happily) had to dig into my iMac’s bowels to see if the conflict might be there.
At the moment I’m on the latest (last ever?) update of El Capitan and I’d understood that any EFI upgrades came embedded within the OS updates as they were incorporated - or is that a misunderstanding as well?
A couple of examples of what spurred me to try and give my iMac a new lease of life can be found in the following links:
https://www.youtube.com/watch?v=JmLkRk3Z...
(even if his technique is a bit off)
and a whole series of articles like this from a well respected blogger, with very specific details regarding what will and what will not work:
https://lowendmac.com/2018/penryn-t9300-...
I’m running a Mid 2007 24” iMac 7.1 that I’ve had from new - apart from the screen size, just like the example used in the youtube I referenced. Is it possible there is some subtle difference I don’t know of that is foiling my attempt and could you point me in the direction of finding it please. It does seem a little hard to take that all of the youtubers/bloggers are full of it and peddling the theory for some reason best know only to themselves - unless, perhaps, to capitalise on the disposal of an excess of unsaleable T9300/500 CPUs?
Will
Update (06/30/2020)
It’s fixed!
It was a dud T9500. The replacement worked and booted straight up as soon as fitted.
No one was ‘at it’, it’s not a myth, it works and was a bit of an undertaking but with care and attention, quite possible. The only thing not reported correctly is the CPU details and the FSB speed. Who cares? It is working and markedly quicker. Most importantly it allows upgrades to a later OS.
To upgrade to Catalina, Dosdude1’s tutorial is excellent and all his patches and updates work well. Just make sure you follow it to the letter. I would put an image of ‘About this Mac up but can’t see how.
A 13 year old iMac, running Catalina, for the outlay of £125 and a few hours of work and effort.
Will
Is dit een goede vraag?
971 
There is still a bit of difference between the 20" and 24" firmware which could be a factor as the 20" has a Radeon HD 2400 XT and the upper end 20" and 24" have a Radeon HD 2600 PRO GPU.
I attempted one and I failed too (an Extreme CPU)!
door Dan
Hi Dan
I'm on the same ATI Radeon HD2600 PRO, so is it that and the firmware to support it causing the collatteral damage and stopping the system recognising the CPU?
It would be nice to find out the real reason, then maybe see if there's a firmware patch that will solve the problem.
I hate throwing perfectly good stuff away (ask my wife :-() and this faithful old iMac has proved to be worth every (expensive) penny I spent 13 years ago - but shouldn't be junked just because it's old.
Will
door Will Noble
@willumn - Sorry guy I have no answer here ;-{
Did you try a second CPU? Could you have a bad one?
If you find one let us know!
door Dan
The seller has sent another one today - but it's from China. They are claimed to be 'New', or 'Opened, never used' and working. Always a lottery with something like that and I don't really know who to go to to test one - other than asking someone with a known functioning system on a T9500 to open it up and swap it to see. A !&&* of big ask.
I'll let you know how things go. A definitive answer on all aspects of this would be good to pin down, since there are so many Macs that could get a new lease of life from the upgrade.
Will
door Will Noble
Hi @willumn, good to hear you resolved the problem! I have a 2007 iMac 21". I also replaced the CPU with a T9500. The computer boots and works fine. I see two problems. I can no longer read the SMC and the CPU is being reported as a Core 2 Duo 700 MHz. And the fan spins at 100%, which is very annoying. I wonder if you experience any of these problems too.
Wim
door wimh
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