Single 12V rail vs split 12v rail

[Mezoxin]

6 hours ago, mariushm said:

You can use pci-e 6/8 pin to EPS adapter cables.  Use higher quality ones and you'll be fine

 

For future reference, the miniFit Jr. series connectors (the ones used for pci-e 6/8 pin, eps, 24pin atx) are rated for 9A of current per pair of pins.

So the EPS connector could do at least 4 pairs x 9A x 12v = 430w

For safety and other reasons, the ATX standard limits to 7A per pair, so they say one EPS connector for 4 pairs x 7a x 12v = 330 watts.

 

Same, pci-e standards limit the pci-e 6pin to 75w and pci-e 8 pin to 150w even though both have the same number of current pairs, 3.  So the connector can actually safely carry 3 pairs x 9A x 12v = 324 watts, though you shouldn't use the connectors to their maximum.

Ideally, you'd get an adapter cable that converts 2 pci-e 6pin connectors to a single EPS, by taking two pairs of wires from each pci-e 6pin, so you'd have the current spread across 4 pairs.

Or you could make your own ... buy two adapter cables and a pin extraction tool, and move one pci-e connector to the other adapter cable.

 

However, my advice would be to buy a power supply that has the same pinout for pci-e and eps headers on its case, like for example Seasonic Prime 1300w : https://www.newegg.com/seasonic-prime-gold-ssr-1300gd-1300w/p/N82E16817151208

It comes with 8 pci-e / eps connectors on the case, in which you can plug either EPS or pci-e , the psu doesn't care.

You can go on Cablemod and order EPS cables for 10$ each: https://store.cablemod.com/configurator/

 

The 1000w version has only 6 connectors, so if you can manage without pci-e connectors, you can have your 6 EPS connectors with that as well.

 

that was very informative thanlk you , where can I do further reading about the minifit jr connectors and the ATX standards 

 

I would prefer though specially with a old server motherboard with so many connectors and high power draw to use a multrirail PSU for safety reasons  such as the one spotty reccomended the AXi 1600 also its Flextronics-based platform and flectronics manufacter serever PSU

[Mezoxin]

9 hours ago, Spotty said:

At stock that would probably be true for most...

The HD7990 came with 2x8pin connectors and was spec'd at "375W" stock, and while it stuck to that limit in most gaming loads it could actually draw much more than that in synthetic compute workloads. Then there's overclocking as well (not that you'd be able to keep it cool enough to overclock it).

https://www.tomshardware.com/reviews/radeon-hd-7990-devil13-7970-x2,3329-12.html

 

 

wow that is crazy , i know intel TDP definition excludes certain instruction sets such as avx loads and also assume that you are following intel power level specifications for PL1 and PL2 and tau all theoe things though are ignored by motherboard manufacterers thats why something like a stock 9700k has a tdp rating of 95w but when i run avx loads using prime 95 i have noticed it reaching 184 watts through my corsair i link , cpu temp was also suggestive of that sort of power draw was correct 

Do GPU's have a clear definition as intel to what are thier power draw specifications are based upon ?

these HD79xx were very power hungry gpu's I remember i even had an HD7970 mobility card in my alienware laptop a while back when in load it blew up the power cord that came with the power brick