Dell Optiplex 755 what cpu to upgrade

I agree with william p above, I have an older Dell Optiplex 780 DT edition, lucked up big time on eBay, not only got the PC, also a Windows 7 Pro refurbishers COA & Intel Core 2 Quad 9650 for $114 shipped! At the time of purchase, didn't even know that the Q9650 was the cream of the crop of the consumer & business line Core 2 Quads (there are 2-3 enthusiast models that consumes a lot more power), these are sold on eBay for close to $100 today if in excellent condition. So that's what I say the night I purchased that PC, I truly lucked out.

I'd like to find a mid tower Optiplex 780 case for cheap, that way can upgrade the PSU & add a decent GPU, as it stands, am limited to short cards, purchased a low profile bracket for the Dell OEM Radeon HD 7570 (1GB GDDR5), which needs no connector, it draws it's power from the MB.

Today, close to two years after purchase, wouldn't consider taking 2x what I paid for the PC, as the Q9650 is a classic Core 2 Quad. There are some other Q9xxx series (the Q9550 being the closest with same 12MB L2 cache), the others starts to drop in performance, on the other hand costs less also, still should be able to snag a Q9550 for $50 with some luck. Keep in mind that once the L2 cache drops to 6MB, not only the GHz level, also the CPU as a whole drops in performance, as that cache is the internal memory of the CPU. Unlike the 1st gen i7's to follow, there's no L3 cache, so it's best to get as much frequency & L2 as budget allows.

Otherwise, the PC will be slow, I have another of the same year, with the best Core 2 Duo (E8600, 3.33GHz), while fast then, slow by today's standards, one's security alone will soak a lot of the performance of these, so I cannot recommend one, even though these are $15-20 on eBay, under $15 for the more popular E8400, which runs at 3.0Ghz & both models features 6MB L2 cache.

BTW, the Optiplex 780 with the Q9650 is running the Windows 10 Pro Creator's Edition w/out a hiccup. While I know that at some point, there'll be a release that'll require additional instruction set to run, still great to see past gen hardware running the latest of Windows OS's. When the day comes that the latest W10 no longer supports the chip, will install Linux Mint & keep on trucking!

Good Luck in finding a quality CPU & make sure that there's a heatsink with a copper base, some of the aluminum block type coolers supplied by OEM's won't cut it for a Q9xxx series, as these are 95W CPU's. I also recommend getting a small tube of Arctic Silver 5 thermal paste & just a pea sized drop is plenty, lower the heatsink as straight as possible & give a very tiny wiggle before tightening the CPU screws, in a criss-cross pattern, just barely snug the first time, keep working around until all are tightened, about 3-4 rounds total. This help to further ensure the thermal paste is spread, and download a software such as Process Lasso CPU Eater Demo along with Core Temp to keep eyes on the temps. the AC5 thermal paste takes up to 200 hours of normal use to fully cure, this can be accelerated by running CPU Eater Demo.

At first, go with the default 60 seconds, then increase to 600 seconds (10 minutes), run this for a couple of rounds, then increase to 20, then 30 minutes. Over time, the CPU will idle at lower temps, at a much faster rate than if you mother uses the PC alone just for transactions & emails, which will take much longer for the paste to cure. You'll be also testing the CPU to make sure it's good at the same time, and CPU Eater is a safer alternative to Prime95, proff is that you should still be able to use the PC for other tasks.

All the Best,

Cat