[SOLVED] Power Supply calculators say I need less Watts for my overall system than the manufacturer says I need for just the GPU, which should I follow?

Nov 12, 2020
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Hey, so I'm planning on upgrading my graphics card from a GTX 1060 6GB to an RTX 2070 8GB with no other change in components for the PC except maybe the PSU (hence the question).

I've input my specs with the new graphics card into various wattage calculators, and all of them have been under 450W for my entire system, which is the capacity of my current PSU (Corsair 450W VS Series). However, the user guide for the RTX 2070 states a minimum of 550W is needed, just for the GPU.

What's up with this? I was hoping I'd get away with not having to buy a new PSU, will I have to, even if the wattage calculators said I'd be safe? Thanks in advance!
 

Wolfshadw

Titan
Moderator
The graphic card power recommendation is for the entire system; not just the graphics card. However, they do tend to overstate the recommendation as they cannot know what else you have installed in your system. They don't know if you have a 35 watt processor or a 220 watt processor installed.

The problem with power supply calculators is that they do not take into account the age of a power supply. When you purchased it, sure, it could handle the load. Today, not so much.

My recommendation is to look at the TDP of your processor. Add in the max wattage your graphics card COULD take (75 watts from the PCI-Ex16 slot plus 75 watts for each 6-pin PCIE power port and/or 150 watts for each 8-pin (6+2-pin). Add another 100 watts for the rest of your system and some overhead. That's the wattage power supply you should be looking for and if your current power supply is close to that amount, I would seriously recommend replacing it.

-Wolf sends
 

Wolfshadw

Titan
Moderator
The graphic card power recommendation is for the entire system; not just the graphics card. However, they do tend to overstate the recommendation as they cannot know what else you have installed in your system. They don't know if you have a 35 watt processor or a 220 watt processor installed.

The problem with power supply calculators is that they do not take into account the age of a power supply. When you purchased it, sure, it could handle the load. Today, not so much.

My recommendation is to look at the TDP of your processor. Add in the max wattage your graphics card COULD take (75 watts from the PCI-Ex16 slot plus 75 watts for each 6-pin PCIE power port and/or 150 watts for each 8-pin (6+2-pin). Add another 100 watts for the rest of your system and some overhead. That's the wattage power supply you should be looking for and if your current power supply is close to that amount, I would seriously recommend replacing it.

-Wolf sends
 

jay32267

Illustrious
In general I think the manufacturers go a little high in their recommendations.

Although I think one reason they may do this is so people that buy crappy supplies that don't output what they say on the label will still work.

But...personally I like overhead...and I would probably go with 550 if I were in your shoes...but that doesn't mean your 450 won't work just fine. It's just cutting it closer than I probably would.
 

Math Geek

Champion
Ambassador
The graphic card power recommendation is for the entire system; not just the graphics card. However, they do tend to overstate the recommendation as they cannot know what else you have installed in your system. They don't know if you have a 35 watt processor or a 220 watt processor installed.

The problem with power supply calculators is that they do not take into account the age of a power supply. When you purchased it, sure, it could handle the load. Today, not so much.

My recommendation is to look at the TDP of your processor. Add in the max wattage your graphics card COULD take (75 watts from the PCI-Ex16 slot plus 75 watts for each 6-pin PCIE power port and/or 150 watts for each 8-pin (6+2-pin). Add another 100 watts for the rest of your system and some overhead. That's the wattage power supply you should be looking for and if your current power supply is close to that amount, I would seriously recommend replacing it.

-Wolf sends
that's exactly how i calculate needs as well. max your cpu can pull (if oc'ed look for watts used when oc'ed), max you gpu can pull through total connections, 100w for rest of the system and then add 20% for overhead and those little extras we don't think about much. that's the minimum you should be looking at. since you'll likely be between psu models, rounding up gives that last bit of buffer for future use.
 

DSzymborski

Polypheme
Moderator
And yes, you ought to buy a new PSU for an RTX 2070; the Corsair VS has become an excellent PSU in its latest incarnation, but you ought to be more ambitious with the quality with a GPU that's likely costing you $400-$500.
 
One of the biggest issues right now with buying a PSU, is the cost is much higher or at least it appears to be higher. Back in 2013 or 2014 when I bought my Corsair AX 760 80+ Platinum, it was around $105 after rebate and the CX 650 was going for around $50-65 depending on rebates. Right now, even a 550watt PSU can be as much as $80-100 if you can even find it in stock. Better quality or higher wattage PSUs will eat up more of the total system budget. Now more than ever, you have to account for higher PSU costs when buying a high end GPU.

My advice is to buy a PSU with at least 100 watts more than is recommended for your GPU by the manufacture and has minimum 1x6+2 pin and 1x6 pin PCIE rails with 2x6+2 pin being more ideal with 650-850watt PSUs. It ensures you have headroom for more or different parts in the future.
 

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