Alienware Aurora R5, Intel i7-6700K, 8 GB DDR4 Memory, 250 GB Samsung SSD, Nvidia GeForce GTX 1070 video card, Windows 10 x64
I should start off by saying that I'm not sure about the long term reliability issues of upgrading a Dell Optiplex with a Q6600 GO(SLACR). So to err on the side of caution, I would follow SpeedStep's words if I was planning on keeping my Optiplex 745 for as long as possible.
That being said--these are the computers I have successfully swapped in a Q6600 GO which have performed flawlessly even under load--well at least initially:
2 Optiplex 745 desktops
2 Optiplex 755 desktops
1 Optiplex 330 desktop
1 Dimension E520 tower
I am currently in the process of installing a Q6600 in a Optiplex 745 SFF which I purchased from eBay for $9.00. Gotta love those auctions!
Heck, I even attempted to install various Core 2 Duo and Core 2 Quad CPUs in an Optiplex GX620--but to no avail. Some claim to have successfully done it but I'm guessing they probably needed to tinker around with the BIOS, to put it mildly.
I thought I should add that of all the computers and CPUs which I have used to perform such upgrades were used/refurbished and purchased from online sites such as eBay and Amazon. So even if one is on a budget, nowadays it is possible to build a Intel Core 2 Quad based Dell computer for under $100 (e.g., $50 for a used Q6600, $50 for a used Optiplex 745 on eBay). I'm not ready to spend $700+ on a Core i7 desktop. I'd rather build 7 Optiplex computers equipped with Core 2 Quads LOL!
I just want to say that I have purchased very cheaply on Ebay (£25) an old OptiPlex 745, and using old peripheries created a very useful machine. Running the old Pentium D it came with it was a trial of patience to use, but with the q6600 (SLACR) and the most recent BIOS, it runs very sweetly indeed. The Pentium TDP is 95W, as is the q6600 (SLACR) TDP, and under 100% loading the hottest core topped out at 71 degrees C (HWMonitor I believe). I do have an ultra sff model with the copper heat tubes heat sink, which I suspect helps.
But considering the age (and the cheapness), this is a fantastic little combination!