I first had to determine was what type of socket it had so I would be able to choose a proper processor upgrade. I have a "YP696" motherboard. Apparently there are some 740s with 939 sockets out there, but most are AM2 sockets. I'm not entirely sure whether I have an AM2 or an AM2+ socket - if I find out I'll update this. The AM2+ processors will work in an AM2 slot, just without the cores being individually powered and no Hypertransport 3.0.
The "YP696" motherboard is also an "enhanced" version which has 8MB of VRAM and can support up to a Phenom X4 9850 whereas the non-"enhanced" boards top out with 64x2 Brisbanes.
The "desktop" form factor also appears to only support 95 watt processors. Dell's larger "mini-tower" does support 125w though, so I'm not sure if it is a hard limitation or just recommended because the "desktop" PSU is less powerful than the "mini-tower." I decided not to chance it.
Another note about sockets, I did consider putting an AM3 CPU into the AM2 socket, they are fairly inexpensive and creep up above 3GHz, but for them to work the BIOS firmware needs to support AM3 and I could not find any reports of people putting these in Optiplex 740s and did not see any mention of AM3 support in the 740 firmware release notes.
With all of this information gathered I looked around for an AM2+ 95w Phenom x4 processor. The one I finally decided to purchase was a refurbished AMD Phenom X4 9750 2.4GHz p/n: HD9750WCJ4BGH. I would have gotten the 9850, but I could not find one for under $100, the refurb 9750 was only $72.
After I received the CPU the install went like so:
- Disconnect everything
- Open up the 740
- Take off the heatsink/shroud combo
- Clean the thermal paste off heatsink
- Release ZIF socket lever
- Carefully remove old 4400+ CPU
- Carefully insert new 9750 CPU
- Push ZIF socket lever back into position
- Apply new thermal paste (Pea size drop of Arctic Silver, spread flat with credit card)
- Reattach heatsink/shroud combo
- Close 740 case
- Reconnect everything
- Push power button
- Cross fingers!!! .. ... ...
- ZOMG BOOT SCREEN YAY!
- Press F2, look at processor info, WOOT! PHENOM!
I should also mention that I have installed a low profile nVidia 9600GT video card (Galaxy 96GFF6HVDCXX GeForce 9600 GT 512MB 256-bit DDR3 PCI Express 2.0 x16 HDCP Ready Low Profile) which has worked well so far, it's not too loud and even though I thought the PSU would be underpowered for this card I have had no issues at all!
In the end, this computer serves as a powerful and compact media center and gaming machine which is exactly what I wanted from it.
My hope is that others will be able to save time gathering information by reading this post.
If you have anything to add or see that something needs to be corrected please leave a comment and I will update this as soon as I can.