Interestingly, from what I could observe, the overall compute load was much lower than for GPUGrid (ø 70% vs. 100%) and similar strain on the 3D engine. What does/could cause the spike in wattage draw even though I cannot observe what is causing this? Any ideas? I just don't understand how a GPU can draw more power even though overall utilisation is down... What am I missing here? Any pointers appreciated

The GPU usage reading shows the utilization of the "task scheduler" units of the GPU, not the utilization of the "task execution" units.
The latter can be measured by the ratio of the power draw of the card and its TDP.
Different apps cause different loads of the different parts of the GPU.
Smaller math tasks can even fit into the cache of the GPU chip itself, so it won't interact with its memory much (making the "task execution" units even more busy).
The GPUGrid app interacts a lot with the CPU and the GPU memory.

Thank you Zoltan for your answer. As always much appreciated.


Also I have to finally share with you what components I chose for my system. I guess, after all the advice I have received from you, I owe you at least a short update on my project, that the thread was initially all about. (but ended up to be so much more)

My main motivation for the chosen parts for my first system build was a) longevity, b) efficiency, c) headroom for future upgrades. While I went a bit over budget, I am happy to finally have ordered all parts. Depending on how smooth the build process will work out in the end over the holidays, I am planning to bring the new system online in early 2021.

The supply shortage of the 1600 series cards honestly took me by surprise as I thought that everyone would only be looking into the Ampere cards. While back in Sep/Oct the supply still seemed decent and pricing fair, the 1650 Super and 1660 Super cards were nowhere to be found. After a couple weeks now seeing absolutely no stock, I discovered some retailers getting the cards back in stock and I pulled the trigger. I settled for a 1660 Super. At the time of purchase the prices for the Asus Strix 1650 Super and 1660 Super cards were 215€ and 255€ respectively and the price differential was too small to justify going with the 1650Super IMO. In the end, I believe this is still worth the money and a great addition to the new system. Adding to that difficulty, I didn't anticipate that many people upgrading to Ampere apparently also had to simultaneously upgrade their PSUs. Thus, it was just impossible to find any 750W+ PSU. This was the last component missing and is now in transit. Thanks again for helping me out here over in the hardware thread as I wasn't sure about the 4-pin EATX vs. 8-pin EATX connectors.

Specs:
- CPU: Ryzen 3700X
- GPU: Asus Strix 1660 Super Adv.
- RAM: 16 GB DDR4 3200MHz 16-18-18-36
- PSU: Platinum 850W
- Mobo: "higher-end" Asus B550 (2 x16 PCIe gen 4 slots in dual x8 mode, 1 x16 PCIe gen 3 slot in x4 mode)

Definitely gonna be a steep upgrade from my current setup:
- CPU: Intel Xeon X5660
- GPU: GTX 750 Ti
- RAM: 12 GB DDR3 ECC 1333 MHz
- PSU: Bronze 475W

My update path I plan to execute on in the future is the following.
- CPU: upgrade from Zen 2 8 core to Zen3 16 core CPU (5950X) or waiting for Zen4 and new chipset/socket
- GPU: from single GPU GTX 1660 Super to dual GPU system by adding a RTX 3060Ti/3070
- RAM: upgrade from 16 GB to 32GB