This isn't meant to sound shitty: It's been my experience that if someone asks if they need a Xeon, they usually don't need a Xeon. They are quite expensive to build and you have to make sure you can cost justify every thing you do in trading. My old T7500 died a couple of years ago as well, I went the i9 route and have absolutely punished the workstation with zero issues. I'd also recommend that you build it yourself, buy parts engineered to stand up to overclocking, never overclock, stay away from OC gaming memory, and don't buy into water cooling (this will be an unpopular statement). A good case and a big brown fan, will have you modeling and trading at any level you want.
Sounds like max stability for trading is more important than using it for leisure. If so, I always recommend the vps from www.ninjamobiletrader.com Here's a personal experience story. I'm daytrading ES and use market if touch orders for profit targets and simulated stops for stop losses (https://ninjatrader.com/blog/why-do-traders-use-simulated-stop-orders/). I like these order types because they are hidden from the order books, but the flip side is that they only live on your local computer and are only submitted when the price is hit. So I'm daytrading with 10 contracts as usual, and my internet goes down, which at that time never happened before. I scramble, restart modem and router, and by the time I reconnect the price is well past where I would have been stopped out and I was left with thousands in loss in excess of the stop loss. From other day traders I've spoken with, anyone trading every day will inevitably have a situation where their internet connection or computer craps out at the worst possible time, leading to a large loss.
It's all ECC RAM but it's "mix and match": 2 sticks of 8GB and 4 sticks of 4GB (32GB total). Does it matter if the RAM is configured like this?
No, you're fine. You can mix sticks of different size, but you cannot mix ECC and NECC. In older model Dell mobos, you could use either ECC or NECC, your choice. In newer models apparently you have the choice to run "Xeon + ECC", or "i5/i7 + NECC". Still can't mix RAM types. (In case you don't know... NECC RAM has 8 chips. ECC RAM has 9 chips. The two together can't be in synch. Personally I don't think ECC RAM for trading is worth the extra cost... but when you can get it cheap in a used computer, that's OK. The price diff between the two types used to be larger... has been coming in over time.)
Is there any performance advantage when you match the sticks in even sizes as well, i.e. 4 x 8GB sticks vs 2 x 8GB sticks + 4 x 4GB sticks that came with my rig?
The 5810 is quad channel (?) if I recall. Slightly better performance might be had if all 4 channels are populated with the same size sticks.
My 5810 comes with the 425W power supply and AMD FirePro W2100 2GB DDR3 vidcard. I'm currently running a dual monitor setup and want to upgrade to 4 monitors. The vidcard has only 2 outputs and will only support 2 monitors AFAIK. Should I upgrade the vidcard or just add another identical AMD FirePro W2100 2GB? Thanks.
Given the current pricing of cards, I would just ebay that 2nd FirePro for $20 bucks. I am assuming the current card has worked for you. If for some reason you should decide to get a big video (gaming) card with an additional 6-pin power connection, you may find that you will be unable to close the side panel because of contact with a bulky side panel latch mechanism. You will then need an angled plug adapter. I almost took a metal grinder to my case before I found this. "ATX 6Pin Female to 6pin Male 180 Degree Angled Power GPU Adapter"
I picked up a FirePro W4100 with 4 ports on eBay for around $50 before I saw your post. It's an official Dell supported card for the 5810. I read there may be a slight chance of system stability issue if you run 2 cards when you can go with just 1 for not a whole lot more. Let's see how that works out. Thanks.
FWIW... I've run 2 video cards mostly over the years. Even ran 4 cards way back before there was much in the way of dual/quad cards. Never had any kind of issue.