If a Corsair SF750....
If a Corsair SF750....
CPU:
CPU cooler: Yes
Motherboard: Yes
Ram: 16GB
SSD/HDD: 500GB SSD
GPU: None specified
Chassis: Yes
OS: Windows 11
Monitor: Yes
PSU age: 5 years
Completely unfamiliar.
Everything from nothing, a complete failure of all related aspects.
CPU model: I9-9900K
Cooler: Apogee Drive II featuring a 140mm x 140mm x 45mm copper radiator with Noctua NF-A14 fan
Note: The loop will incorporate the GPU into a Bykski water block
Motherboard: GIGABYTE Z390I AORUS PRO WIFI W/AUXILLARY 60MM VRM COOLING FAN
RAM: KingBank DDR4 4000MHz, 16 GB x 2
Storage: 4TB NVME for System Drive and 4TB NVME for Storage Drive
GPU: ASUS RTX 3070
Chassis: Custom design with a flat breadboard-style loop layout
Operating System: Windows 11 Pro
Monitor: 65" Plasma TV; resolution capped at 1080p
Power Supply: TBD – I own both a Corsair SF750 and a Lian-Li SP850. I prefer the SF750 for quieter operation, but another forum suggested an 850W PSU due to the RTX 3070’s power needs. Either option would work, though an SF850 would cost more than the SF750 plus an SP850.
Risk Assessment: I recognize the SF750 has some limitations, yet it tends to shut down cleanly during overcurrent events. I need to weigh whether potential downstream damage from such a surge is worth the risk.
In short: What should you decide about the PSU choice?
TIA, and thanks for all the feedback so far!
Larry
I wanted to thank everyone who took part again.
After rechecking the review on tom'sHARDWARE, I was surprised to find that the OCP was set to 146% of the rated current—about 1100 Watts!
That’s much higher than what even an overclocked RTX 3070 would handle as a surge.
So I’m confident in my choice: I’ll use the SF750 and bring back the Lian-Li SP850.
Unless there’s proof someone has an RTX 3070 drawing that much power, I think this clears up my doubts!
Larry
I might have shared something in another discussion, but I've been using an 11600K on a (reference*) 3070 for quite some time without any problems with either an SF or RM line of Corsair 750W. Knowing that certain partner cards offer very different power curve options.
Thank you for your reply. You're among the few whose views I've come to trust. Now, could you please let me know which forum is best for sharing a build log or where to post tips and techniques? From what I've seen, the "Opinions and Experiences" forum seems like a place where content tends to disappear and discussions are rare!
Larry
I agree with this suggestion, though during Techpowerup's evaluation of the RTX3070 they mentioned a TDP of 220W and advised using a PSU of at least 550W.
The i9-9900K features a PL2 TDP rating of 119W.
If we consider a basic scenario without any extra GPU or CPU overclocking, I estimate your system could use around 220W (for the GPU) + 120W (for the CPU) + 60W (for M.2 and storage) = approximately 400W, excluding any temporary spikes.
It's improbable that both the CPU and GPU will operate at full capacity outside of benchmark tests. Most likely, you'll draw between 100W and 300W generally.
Even if it reaches 400W, your GPU might still manage to draw another 350W from a strong 750W PSU, or possibly more depending on the PSU's capabilities.
Unless you've encountered issues with the SF750 in the past, I recommend giving it a shot. You could always upgrade to an SP850 if needed.
I would need to review additional PSU articles, but it seems reasonable that the 127% OCP on the SF750 could be activated by prolonged overloads exceeding one second.
Short, intense current surges of about 150 to 200%, lasting a few milliseconds, might not trigger the 127% OCP. The PSU is likely built to handle brief spikes but react to longer durations.
The performance hinges on how much energy the 400V electrolytic capacitor stores and the MOSFET ratings. Adding a large capacitor and oversized MOSFETs should allow them to manage short bursts well above the PSU's steady-state limit.
Certain PSUs are better suited for these intermittent loads, while others might fail and trigger the OCP.
Give it a try and observe the results.
Similar personal stories come to mind. I used the same setup with an SF 750 and a 11900K, upgrading from the 3070 to an RX7080XT while keeping the same power supply. No problems arose with the power supply.
The same power supply is now housed within a refresh of that system: a B550 Tomahawk WiFi Max board equipped with 4X RAM, RX7800XT (2x NVMe SSDs, including a 990 Pro and one 2.5" SSD), and a total of 9 fans, including the cooler.
I regularly charge a wireless keyboard, power a bike light, use headphones, Xbox controller, phone, etc., and often run an external USB-powered drive for backups. I usually stay in the middle of BG3 griding and rarely notice power draw exceeding around 525W as reported by my APC UPS. In fact, the cooling fan on the SF unit hasn’t turned on yet, and there’s no dust visible on its working side.
As discussed before, I understand the differences between reference power profiles and partner card voltage curves, but I think the advice about using more PSUs is unnecessary here.
Just my .02