All the one's I've seen use the common CR2032 lithium coin battery. $2 or less, available everywhere. Amazed simply replacing the battery might fix your problem? As I said earlier... when the mobo battery gets close to drained, the computer can act squirrely. Not sure replacing the battery will solve your problem, but it's an easy and cheap thing to try. (If you have a multimeter, you can check your current battery to see if it's low before you buy a replacement.)
A T5810 will be fine. (HP and Lenovo have equivalents, but Dell's are almost always lower priced.) Suggest CPU of Xeon E5-1620v3 or better as a minimum*. 8GB of RAM may be enough (is for my trading rig) or 16GB if you prefer. SSD, of course... adequate video card(s) for your monitors. You can get all of that for easily <$500. You probably can't "over-spec" such a machine unless you go overboard on the RAM or overkill on the CPU. *If you are graphing and archiving tic data, you're probably going to need the most powerful CPU you can afford. The T5810 supports the Xeon E5-16xx and E5-23xx series of CPUs. Pick from the higher end of either of those.
If you do this, careful not to push or pry too hard, those old motherboards get pretty crispy and fragile. treat grandma with tlc, lol.
I changed the battery and I had no luck, its the Motherboard so will need to replace the Workstation/grandma. It was worth trying as the battery was less than $2.00. Thanks for all the help. By the way it would be quite easy to fatfinger the motherboard when changing the battery.
"it would be quite easy to fatfinger the motherboard when changing the battery." I though the expression fatfinger only applied to incorrectly entering a stock/futures order. Ha!It seems the definition has widened over time.