Please help a noob figure out what size PSU to order

3080guy · 12 Oct 2020 at 19:38

Im not sure how to go about figuring out which PSU I need size-wise.

I have a 650 watt psu and want to be safe, so Id like to buy a 750watt psu, prior to ordering a 3080. I dont want to order something that wont fit my case.

How do I use windows or my eyeballs to figure out what size PSU I have.
Also, are there a few generic sizes, with size names, or is it not that simple.
I have no idea what to look for with regards to ordering the right sized psu.

(I also think my 650 watt psu will run my pc and a 3080, but Id like more overhead room and to use a 750watt psu).

Thanks for your help guys.

The_Arbiter · 12 Oct 2020 at 20:08

Should say in your case manual. It'll just be 150mm standard ATX more than likely. But small cases will differ.

Vince · 12 Oct 2020 at 20:12

3080guy said:
Im not sure how to go about figuring out which PSU I need size-wise.

I have a 650 watt psu and want to be safe, so Id like to buy a 750watt psu, prior to ordering a 3080. I dont want to order something that wont fit my case.

How do I use windows or my eyeballs to figure out what size PSU I have.
Also, are there a few generic sizes, with size names, or is it not that simple.
I have no idea what to look for with regards to ordering the right sized psu.

(I also think my 650 watt psu will run my pc and a 3080, but Id like more overhead room and to use a 750watt psu).

Thanks for your help guys.

What case is it?

3080guy · 12 Oct 2020 at 21:08

I think I have this...
https://www.corsair.com/uk/en/Categ...ed-Glass-Mid-Tower-Smart-Case/p/CC-9011173-WW

So I need to figure out the correct size PSU.
Im learning loads, wondering out loud if a GOLD or better PSU is worth it (fairly heavy use) to help save on electricity, which adds up over the years.
Thanks Arbiter, Vince.

OvEr_KiLL · 12 Oct 2020 at 21:15

says on tech specs
'' Maximum PSU Length
180mm ''

i would get a decent 850w for a bit of head room
https://www.overclockers.co.uk/supe...old-modular-power-supply-black-ca-062-sf.html 7 years warranty
https://www.overclockers.co.uk/phan...old-modular-power-combo-supply-ca-08a-pt.html 12 years warranty made by seasonic

3080guy · 12 Oct 2020 at 21:52

Of the two, is either a notably better brand?
Can I just go ahead and order one of those? (I didnt see case space/size referenced anywhere, so trust you can see dimensions.
Appreciate the help, cheers!

pastymuncher · 13 Oct 2020 at 10:53

I would have said the Phanteks for the extra 5 years warranty but I don't think it will fit. It's 170mm long but then you also need to factor in the modular connectors so with the drive cages in plcae I don't think it will fit. Even the Superflower is 160mm long so once the cables are fitted it's going to be tight. If you don't use the pair of 3.5" drive bays then take them out and there will be no clearance issues no matter which psu you go for.

EsaT · 13 Oct 2020 at 17:27

Phanteks Amp is 140mm long.
https://www.overclockers.co.uk/phanteks-amp-750w-80-plus-gold-modular-power-supply-ca-09r-pt.html

3080guy · 13 Oct 2020 at 19:05

EsaT said:
Phanteks Amp is 140mm long.
https://www.overclockers.co.uk/phanteks-amp-750w-80-plus-gold-modular-power-supply-ca-09r-pt.html

That looks perfect.

I think I could run a 3080 (according to an online calculator) on a 650 psu, but I read somewhere its better not to push your psu.
Someone here linked to a video where a chap ran a 2080 TI gaming rig from a 450w psu, so Im thinking 850 is futureproofing. Dont need 850 today.
Like the look of the super compact 750w Phanteks. Thanks EsaT.

Ive not opened a PC case to change anything in 15 years, hence the noob comment. Nothing looks anything like it used to. Can I do any damage by plugging anything in wrong, or not really? Is watching a few YouTube Videos more than sufficient training when swapping out a PSU?

EsaT · 13 Oct 2020 at 20:04

Nothing has changed from 15 years ago: Do wrong things and there's high chance of something breaking down.

OvEr_KiLL · 14 Oct 2020 at 16:21

make sure you disconnect it from the wall plug first then fit the new one and use the cables that come with it in the box '' dont '' try and use others! thern when its all connected reconnect the wall plug and turn it on
and 1 cable per power slot on a gfx card not 1 cable on 2 slots!!

3080guy · 17 Oct 2020 at 09:30

OvEr_KiLL said:
make sure you disconnect it from the wall plug first then fit the new one and use the cables that come with it in the box '' dont '' try and use others! thern when its all connected reconnect the wall plug and turn it on
and 1 cable per power slot on a gfx card not 1 cable on 2 slots!!

Thanks. The 1 cable per slot Ill remember. Cheers!

3080guy · 10 Dec 2020 at 23:27

OvEr_KiLL said:
make sure you disconnect it from the wall plug first then fit the new one and use the cables that come with it in the box '' dont '' try and use others! thern when its all connected reconnect the wall plug and turn it on
and 1 cable per power slot on a gfx card not 1 cable on 2 slots!!

Can you explain, would new PC's or just older PCs need to use cables from the PSU box? Why are you suggesting not to use existing cables?
Just keen to learn, thanks for your help.

3080guy · 10 Dec 2020 at 23:37

OvEr_KiLL said:
says on tech specs
i would get a decent 850w for a bit of head room

What are all the reasons why headroom would be a good thing in this instance?

Alex h · 11 Dec 2020 at 08:20

3080guy said:
What are all the reasons why headroom would be a good thing in this instance?

More headroom means the psu will be working less so less strain less heat so should last longer as isn't been run full pelt or close to it

pastymuncher · 11 Dec 2020 at 09:29

Better efficiency too. PSU's are usually at their most efficient around half load although there are exceptions.

3080guy · 11 Dec 2020 at 10:27

Thanks guys.
And what of using one cable per power slot on the graphics card - does a 3080 need 3 cables to run from the PSU to the card (3 seperate cables)?

3080guy · 11 Dec 2020 at 10:55

EsaT said:
Phanteks Amp is 140mm long.
https://www.overclockers.co.uk/phanteks-amp-750w-80-plus-gold-modular-power-supply-ca-09r-pt.html

I found out today my PSU is actually 140mm so this would be the same size. Thanks again.
Would I literally need to use 3 seperate cables from this (the three 8-pin connectors?) to a 3080?

EsaT · 11 Dec 2020 at 18:13

While dedicated cable per connector is ideal, two cables with use of one extra daisy chained connector should be enough.
At least for not overvolted to even more crazier power consumption models.

Also 140mm long Seasonic Focus 850W would come with three cables, but stock situation has been bad for long.

3080guy · 14 Dec 2020 at 13:49

EsaT said:
While dedicated cable per connector is ideal, two cables with use of one extra daisy chained connector should be enough.
At least for not overvolted to even more crazier power consumption models.

Also 140mm long Seasonic Focus 850W would come with three cables, but stock situation has been bad for long.

I went through the 850 psus one by one until I noticed those (140mm) and I noted the no stock situ! Well spotted, thank you. It looks like what Id like, in 140mm depth and 850w power.