I agree, the 1080 will be hard to source for the next couple of weeks unless you are open to price gouging. Also not sure if the
1080 FTW flavor will provide any kind of meaningful increase over the stock 1080 in a Resolve environment.
The 1080 Ti at a rumored 12GB is certainly worth waiting for, as is obviously the next gen Pascal-based TITAN at a rumored 24GB. Resolve is all about the GPU and VRAM -- so the new TITAN will probably represent Resolve nirvana -- at least until the next generation technology is released, at which point we'll wonder how we ever used Pascal-based cards.
The internal vs. external video interface decision will play a big role in how the Z820 is configured. I believe HP has not yet released a Z-series TB3 card -- so you're currently limited to TB2. That would still allow you to use an external UltraStudio interface, as opposed to an internal DeckLink card (although the new UltraStudio Extreme is TB3-based). Alternatively, you could use the TB2 as an external storage solution.
Be forewarned that HP Workstations configured with multiple GPUs can sometimes block the PCIe slot that the TB card must be installed in. For example, in the Z820, the TB card
must be installed in PCIe Slot 5.
Now, that might not be a big problem if you are going with an an external TB-based video interface. However, as you can see in the
Table 1: I/O Slot Recommended Load Order, if you have dual GPUs
and an internal video adapter that must be installed in a x16 slot, then slot 5 will likely be blocked.
I would strongly recommend you research your video interface requirements, your intended GPU choices, how others are
currently configuring their Z820s -- and, although long in the tooth, the Z820 Configuration Guide on page 17 of the
2014 DaVinci Resolve Windows Conguration Guide.
Even though I own (and am anecdotally selling) an HP TB2 card, as you can see from my signature, my goal was to achieve maximum GPU performance, maximum video interface performance, and maximum media storage 'read' performance -- without using an expansion chassis. To accomplish this, I needed to walk away from TB.
Lastly, there is one interesting accessory that might represent a solution if you get into a PCIe slot bind. You would need to research this very carefully, but HP manufactures the
highest quality PCIe slot extension cables. Using one of these under one of the blocked PCIe slots in your Z820 might allow you to add a card that would otherwise not be physically possible. However, you would need to make sure there is enough clearance for the extension cable -- as well as consider the implications that the card you add will need to sit loosely within the computer and will not have backplane access.
HP Z840 | Dual 10-Core Xeon 2.3 GHz | Dual TITAN Xp | 64 GB RAM | Media: PCIe SSD 2.5 GB/s
DeckLink 4K Ext 12G | Pocket UltraScope | Avid Artist Color | CalMAN Studio/C6-HDR
Resolve Studio 15.0.0B.043 | Fusion Studio 9.0.2 | DTV 10.9.12 | Win10 Pro 1803