Will the Phenom II x4 run in the Optiplex 740 (Enhanced Edition only)? Don't know all of the details about the Enhanced, only that it has some type of 8MB chip, maybe the BIOS, since it's there regardless of OS installed.
I'd be a bit concerned about running anything above 95W on that board, and not just because of the MB possibly melting, the 280W PSU supplied has to be figured in, if much any type of GPU is installed that requires much power, the PSU will either go, shutdown to prevent damage, if not, and it does go, can take a lot with it. Your CPU/RAM, GPU & SSD (if installed), and of course MB could be fried because of lack of power. While I know that sounds weird, it happens more often than we realize, there's likely a Topic per day about these soft of issues, or a few per week.
On another custom AMD PC that I have, an AMD Athlon II x4 630 with 8GB RAM, is giving me both CPU & RAM WEI scores of 7.2, though I have DDR3 RAM. It also runs at 95W TDP, has a 2MB L2 cache, and am getting (hopefully) a new MB this week, has been ordered from Newegg, just waiting for shipment.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157582
While I know that this won't fit in a BTX type PC, this is the reason why I've gone away from them, and chances are very slim that my Optiplex 740 will see duty again. It's optical drives was removed for the screws, so that I could snip those push pins off of the cooler that shipped with my i7-4790K for my main PC, which is also a Dell, the XPS 8700. Seen the trick online, used alcohol to remove that useless pre-applied paste & applied my favorite, MX-4 instead, it only takes a half of a pea size drop to cover the surface. And no, I don't manually spread, instead, lower gently, have things aligned & give just a tiny wiggle, and then proceed to tighten the cooler in a criss-cross pattern, taking about 5 times on each to snug all down.
Also the CMOS battery was removed to replace a dying one on another PC, and appears to be the same size chassis as my Optiplex 780, loaded to the gills with a Intel Core 2 Quad Q9650 (12MB L2 cache) running at 3.0GHz, the best of the consumer editions, just before the 1st gen i7's were released. Actually there were some higher rated enthusiast CPU of the Q98xx series, probably some of the $1,000 CPU's. My Optiplex 780 also runs 16GB of DDR3 RAM, 4GB x4 sticks, the tricky part was in finding 'double sided' modules. I believe it was said for Crucial RAM, stay away from models that ends in 'J'.
Anyway, will check to see if there's any better looking parts (trim pieces, panels, etc) that looks & fits better, have already swapped the lid. Regardless, will keep the MB, maybe one day, someone who has more appreciation for nVidia chipsets than myself can do something with it. Had nVidia not abandoned the MB market, they could had provided true AHCI drivers, necessary for proper SSD function, and Dell's updated BIOS for it (A15) didn't give pure SATA only support. If so, then one couldn't take any old Dell reinstall XP Pro/Home/MCE (or W2K) reinstall CD, and install, it would stop at the point of proving drivers if this were the case. Even more surprising, all three OS's activated & validated! Keeping in mind that all were official Dell Reinstall CD's that I had accumulated over the years, just wanted to see what would happen.
To be honest, am not sure who provides support for the Optiplex 740, as there's limited drivers for install, I presume these were included in the package on CD, with reinstall media and/or a recovery partition. I know that it shipped with Vista Business, so downgrading to XP Pro was fully legit & many did, but the Home/MCE activations were surprising, to install W2K, all one needs to do is input the correct key, no validation needed. Actually, IMO, W2K was a better OS than XP, because users were limited to what could be installed, and to this day, many industrial machinery runs from the OS (offline).
So for the right person, the Optiplex 740 can be quite a useful computer, sadly there's few & expensive options to place the MB in a mid tower to add more power for even better graphics, and for as much CPU as the Enhanced BIOS allows. If one gets lucky on a given day, an empty mid tower will appear on eBay, and even at $50, will go fast. Unfortunately, there's no mass market demand for BTX mid towers, even though on eBay & other sites, these refurbished PC's are selling like hotcakes.
Good Luck with your project, and hang in there, sometimes what seems impossible can happen, have seen it many more times than I can count.
🙂
Cat