I'm confused. the Newegg website lets you opt in for win10 install on that T3500. could you clarify?
1. I have T3500s running W7, 32-bit. Was planning to try to run W10 on them. I already have the hardware... and if I could run W10 on them, I might get another 5 years service rather than just taking them to the junk yard.
2. Using a Dell Reinstallation Disk, I was unable to get W10 to load. (Appeared to load, but when it looked like it was about finished it stopped and again asked "fresh install" or "repair"?. Tried it a few times... same each time.)
3. Checked Dell's driver support page... they do not have drivers for W10 on the T3500. Not a great surprise, as the T3500 is 2009 vintage.
4. Checked Microsoft's "hardware compatibility lookup" and T3500 is not on the list.
5. I know sellers have T3500s with W10 on them, so I asked one, "How do you do it?" One gave me instructions about getting some file(s) off of W7, 64-bit and then would be able to install W10 (??) But with Dell not providing drivers, some components would either perform sub-par (on W10's included generic/default drivers) or not at all.
When W10 first came out, you could "upgrade your W7 installation" to W10 for free. Not sure how that worked with W7's already installed drivers, but that appears to be different from trying to do a fresh install of W10. ?? (As of May 2018, there was still a way to upgrade your W7 installation to W10 for free. You might search to see if that's still available.)
All in all, I concluded it's likely more hassle than it's worth to try to run W10 on my T3500s. And if I were looking at the prospect of "spending
any amount of $$$ on a T3500 to run W10", I wouldn't do it.
Given that you can buy an HP Z440 for ~$400-ish and that it's 2015 vintage... (has SATA III, USB 3.0, faster RAM and some much faster CPU choices, whereas T3500 has SATA II, USB 2.0 and is 6-years older)... I'm using that as a guide for my own upgrades to W10. For the price differential, going with HP Z440 is a "no brainer". If you go that route, recommend you choose E5-1620 CPU or better. The 1603 & 1607 are slower and run slower RAM.