3080 and old CoolerMaster 850W

washingducks · 11 Jun 2021 at 23:30

Hi all

I've realised after 9 months of waiting for a new 3080 (still waiting, obvs) that it has 3x 8-pin connectors on the card.

My PSU, a 10 year old Cooler Master 850w Silent Pro, only has 6-pin connectors. I do have 6-pin to 8-pin PCIEs kicking around but would I be right to say they're underrated for this pupose and I need to get myself a new PSU?

The PSU is semi modular, the ATX power cable connected to it happilly had enough connectors to suit the new mobo when I upgraded to a Asus X570 Crosshair VIII with 24pin and the 8+4 pin sockets.
If I have to get a new modular unit, do they all come with the ATX power cables and will they suit the Crosshair?

I realise 850W was possibly overcooking it in my previous build. I now have two NVMes, a 360 AIC, 2x240 fans and 1x140, a multi card reader and a DVD-RW. EVGA and PSU calclator at pc-builds suggest a 750W. Does that sound about right to folks?

Cheers all

mickyflinn · 12 Jun 2021 at 21:55

I personally wouldnt want my 3080 on a 10 year old psu.

washingducks · 13 Jun 2021 at 01:36

mickyflinn said:
I personally wouldnt want my 3080 on a 10 year old psu.

I agree with that. New one ordered.

nlel1975 · 13 Jun 2021 at 10:58

Yeah that EVGA power meter is good as it doesn’t underestimate.

bimbleuk · 13 Jun 2021 at 11:08

Not just the peak load but the spikey nature of new GPUs puts a lot of strain on older PSUs. Same as newer CPUs have extra deep sleep modes that older PSUs don't support.

nlel1975 · 13 Jun 2021 at 17:25

The EVGA power meter doesn’t always recommend a 750W PSU, if you’ve got a 3090 with an overclocked 10900kf a single SSD and two mechanical hard drives it recommends an 850W.

washingducks · 14 Jun 2021 at 08:19

Thanks everyone for your input.

I got a new PSU, ROG Strix 750W (dont @ me!) and installed. Sadly, the machine does not power up, I've done all the checks of swtich at the back and cables in securely in sockets but no luck so far. I've put the old CoolerMaster PSU back in for now and everything fires up so that a plus!

EsaT · 14 Jun 2021 at 15:01

Did you change all the cables?
Even if connector fits, modular cables are incompatible between different PSUs.

washingducks · 14 Jun 2021 at 16:05

EsaT said:
Did you change all the cables?
Even if connector fits, modular cables are incompatible between different PSUs.

So I took the PSU out and did the paperclip test which was fine. Plugged it all back in, turned it on, and no joy again.

I'd kept the old cable to the GPU, so swapped that out and bingo, it all works! So you were dead right and I wished you'd been around earlier; you would've saved me a good bit of time. Another learning day, and thanks for the reply - in all the searching around I did, I didn't find that as a possible cause. Hopefully here someone else will find it.

Cheers!

washingducks · 14 Jun 2021 at 16:08

Oh, and I'm also thankful that it didn't all blow up.

pastymuncher · 14 Jun 2021 at 20:03

You are very, very lucky. Never mix cables from other PSU's.

tamzzy · 14 Jun 2021 at 20:06

indeed very very lucky not to have damaged the psu at best, and at worst...fried the whole system.

aimless · 18 Jun 2021 at 10:31

This would run the 3080 perfectly using adapters. I have done this many times. But do NOT use modular cables from other brands.