[SOLVED] SFX PSU for SFF - several points to clarify, please

Jan 8, 2021
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Dear community,

I'm gonna build for the first time within the following config:
  • Case: Dan A4 (7.2L) or Louqe Ghost S1 (8.2L) or FormD T1 (9.5L)
  • CPU: AMD Ryzen 5600X (65W) or 5800X (105W)
  • GPU: Nvidia GeForce GTX 1070 (150W) or RTX 3070 (220W)
With all the other hardware blows & whistles added, my overall TDP will be either ~250W (light scenario) or ~370W (heavy scenario), and these are the points I'll ask you to kindly comment please:

  1. I've thought the good rule of a thumb is to add ~30% on top of TDP, so I planned to go for a 350W PSU (for the light scenario) or a 450W one (for the heavy scenario). However, they say both CPU and GPU may have spikes in power consumption, where GPU's spikes will be occasional and mainly in gaming, while CPU's spikes will be mainly in video rendering and go throughout the whole process. So while they confirmed 350W PSU for the light scenario is OK, the heavy one requires a 550W or even better a 650W one - to "cover" all possible RTX 3070 spikes. Questions: which hardware (CPU or GPU) is more likely to have spikes and when? If all CPUs and GPUs have occasional spikes, why is it particularly my heavy scenario that requires more than +30% (shouldn't the same logic be applied then to the light scenario too - e.g. a 400-450W [instead of 350W] for the 250W TDP)?
  2. Am I right ATX specification applies to SFX form factor too? How much is the version important? I'm not talking about the ATX12VO which is as new as it is useless so far (IMO), but ATX12V v2.51 introduces an Alternative Sleep Mode (ASM), which is supposed to do something (not examined the details yet) with power management.
  3. What are the nice-to-have features/options of SFX PSU? Fan-less/passive mode, modular cable system, flexible cables (individually sleeved and/or insulated with soft silicon rubber) of proper length - anything else? As far as I know fan curve can't be regulated via app (and probably this is not even needed?), but possibly there's something good an an option, which you can recommend?
Thank you guys!
 
Dear community,

I'm gonna build for the first time within the following config:
  • Case: Dan A4 (7.2L) or Louqe Ghost S1 (8.2L) or FormD T1 (9.5L)
  • CPU: AMD Ryzen 5600X (65W) or 5800X (105W)
  • GPU: Nvidia GeForce GTX 1070 (150W) or RTX 3070 (220W)
With all the other hardware blows & whistles added, my overall TDP will be either ~250W (light scenario) or ~370W (heavy scenario), and these are the points I'll ask you to kindly comment please:

  1. I've thought the good rule of a thumb is to add ~30% on top of TDP, so I planned to go for a 350W PSU (for the light scenario) or a 450W one (for the heavy scenario). However, they say both CPU and GPU may have spikes in power consumption, where GPU's spikes will be occasional and mainly in gaming, while CPU's spikes will be mainly in video rendering and go throughout the whole process. So while they confirmed 350W PSU for the light scenario is OK, the heavy one requires a 550W or even better a 650W one - to "cover" all possible RTX 3070 spikes. Questions: which hardware (CPU or GPU) is more likely to have spikes and when? If all CPUs and GPUs have occasional spikes, why is it particularly my heavy scenario that requires more than +30% (shouldn't the same logic be applied then to the light scenario too - e.g. a 400-450W [instead of 350W] for the 250W TDP)?
  2. Am I right ATX specification applies to SFX form factor too? How much is the version important? I'm not talking about the ATX12VO which is as new as it is useless so far (IMO), but ATX12V v2.51 introduces an Alternative Sleep Mode (ASM), which is supposed to do something (not examined the details yet) with power management.
  3. What are the nice-to-have features/options of SFX PSU? Fan-less/passive mode, modular cable system, flexible cables (individually sleeved and/or insulated with soft silicon rubber) of proper length - anything else? As far as I know fan curve can't be regulated via app (and probably this is not even needed?), but possibly there's something good an an option, which you can recommend?
Thank you guys!
1. Plan for worst case scenario and over-provision. Use peak power consumption for CPU and GPU, include 50 watts or so for other parts (board, memory, drive(s)) and add 25% headroom to bring you where you should be. Also take into account future upgrades and adjust accordingly. Since it appears you'll be building in an ultra-small case you might over-provision even more. You probably don't want to rebuild and rewire the thing 2-3 years from now due to an unforseen upgrade.

2. Yes, SFX complies with ATX specs. SFX denotes the overall size of the model. Don't worry about version. Just get a new, high quality PSU and you'll be fine. The A4 and S1 cases you listed can both fit SFX and SFX-L models. The 'L' is a slightly longer version of SFX.

3. Choices for quality SFX are limited to only a couple good models so you can't be too picky about features. They'll have nice enough features no need to worry about that.

These are the 2 models I'd pick for your system. Either is fine IMO and should be enough for a 5800x and RTX3070
 
Last edited:
Reactions: PiffPuff
Dear community,

I'm gonna build for the first time within the following config:
  • Case: Dan A4 (7.2L) or Louqe Ghost S1 (8.2L) or FormD T1 (9.5L)
  • CPU: AMD Ryzen 5600X (65W) or 5800X (105W)
  • GPU: Nvidia GeForce GTX 1070 (150W) or RTX 3070 (220W)
With all the other hardware blows & whistles added, my overall TDP will be either ~250W (light scenario) or ~370W (heavy scenario), and these are the points I'll ask you to kindly comment please:

  1. I've thought the good rule of a thumb is to add ~30% on top of TDP, so I planned to go for a 350W PSU (for the light scenario) or a 450W one (for the heavy scenario). However, they say both CPU and GPU may have spikes in power consumption, where GPU's spikes will be occasional and mainly in gaming, while CPU's spikes will be mainly in video rendering and go throughout the whole process. So while they confirmed 350W PSU for the light scenario is OK, the heavy one requires a 550W or even better a 650W one - to "cover" all possible RTX 3070 spikes. Questions: which hardware (CPU or GPU) is more likely to have spikes and when? If all CPUs and GPUs have occasional spikes, why is it particularly my heavy scenario that requires more than +30% (shouldn't the same logic be applied then to the light scenario too - e.g. a 400-450W [instead of 350W] for the 250W TDP)?
  2. Am I right ATX specification applies to SFX form factor too? How much is the version important? I'm not talking about the ATX12VO which is as new as it is useless so far (IMO), but ATX12V v2.51 introduces an Alternative Sleep Mode (ASM), which is supposed to do something (not examined the details yet) with power management.
  3. What are the nice-to-have features/options of SFX PSU? Fan-less/passive mode, modular cable system, flexible cables (individually sleeved and/or insulated with soft silicon rubber) of proper length - anything else? As far as I know fan curve can't be regulated via app (and probably this is not even needed?), but possibly there's something good an an option, which you can recommend?
Thank you guys!
1. Plan for worst case scenario and over-provision. Use peak power consumption for CPU and GPU, include 50 watts or so for other parts (board, memory, drive(s)) and add 25% headroom to bring you where you should be. Also take into account future upgrades and adjust accordingly. Since it appears you'll be building in an ultra-small case you might over-provision even more. You probably don't want to rebuild and rewire the thing 2-3 years from now due to an unforseen upgrade.

2. Yes, SFX complies with ATX specs. SFX denotes the overall size of the model. Don't worry about version. Just get a new, high quality PSU and you'll be fine. The A4 and S1 cases you listed can both fit SFX and SFX-L models. The 'L' is a slightly longer version of SFX.

3. Choices for quality SFX are limited to only a couple good models so you can't be too picky about features. They'll have nice enough features no need to worry about that.

These are the 2 models I'd pick for your system. Either is fine IMO and should be enough for a 5800x and RTX3070
 
Last edited:
Reactions: PiffPuff
Mar 8, 2021
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How does Fractal Design stand in exactly PSUs vs. reputable units from Corsair, Seasonic, EVGA, Antec? I don't mean to say F.Design is not, just curious..
[/ QUOTE]
I personally would take Corsair SF600 PLATINUM no GOLD,but whatever you take from these models will serve you faithfully.
 
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