Power through PCIe?

[Bros1929]

Hello all, I am new to the world of upgrading my PC and hoping to get some insight in some thoughts I am having. So, assuming all the power reqs and gpu specs are the same, would a card that receives power straight from the psu run faster than a card that gets power from the PCI slot? My thoughts are that sending power through the PCI will cause a bottleneck of data to the card. EDIT: And are cards with no external power supplies lower quality than cards with external power supplies?

 

[robax91]

No. There are parts of a PCI slot that are dedicated to power, so they won't send data regardless of the extra power needs of the card put into the slot. The data rate is limited by the chipset/gen of the PCI slot. The two do not really interfere.

Ex. You have a Nvidia 750ti and an AMD R7 265. Both are decently fast for moderate gaming. Both take board power, but the 265 also has a 6pin power requirement. The 750ti is not being held back by it's lack of a 6pin, it just uses the power it was designed to because of its efficiency.

However, if you compare a 750ti to an AMD R9 290x or an Nvidia 980, they use multiple 6 pins, and do require more power because of their chips. And they are far superior. Did this help any? Your question is kinda vague...

 

[ThatVietGuy]

A bottleneck doesn't exist in sending power.

The reason a card needs extra power from the PSU is because it's more robust and needs that power in order to be functional. So, of course it'll run faster than a card that's only supplied by the PCIe slot - IT'S DESIGNED THAT WAY.

 

[rhysiam]

The PCIe spec allows for up to 75W to be delivered through the PCIe interface. It does this without any impact on bandwidth. So no, receiving power 'directly' from the PSU doesn't impact performance.

The issue is that 75W is nowhere near enough for high performance cards. Even the extremely efficient GTX 970 & 980 require 145W & 165W respectively. Because of that, the cards have additional power connectors to ensure they don't exceed the PCIe spec by drawing too much power. Most will still rely on some power through the PCIe interface, it's just supplemented by additional connectors.

It's not necessarily the case that cards without additional power are 'lower quality', but good cards tend to be power hungry and require additional power. Efficiency does still come in to play however. The 750TI which doesn't require additional power is actually faster than many cards that do. But if you want a mid or high range card, they all exceed the 75W limit.

 

[renz496]

Hello all, I am new to the world of upgrading my PC and hoping to get some insight in some thoughts I am having. So, assuming all the power reqs and gpu specs are the same, would a card that receives power straight from the psu run faster than a card that gets power from the PCI slot? My thoughts are that sending power through the PCI will cause a bottleneck of data to the card. EDIT: And are cards with no external power supplies lower quality than cards with external power supplies?

first you need to understand the power requirement of a graphic card and how they work. the PCI-E x16 slot can provide up to 75w of power. if the particular card did not exceed that limit then the card will not going to need extra power directly from power supply. and no the power provided by the PCI-E slot have no relation to the data throughput that going across the PCI-E lanes. it is simply more faster card will need more power to properly function hence the need of direct extra power from power supply.