Pcie watt limit

[Amaides]

Does a pcie slot saying it has a 35w limit really make a gpu that exceeds that limit not work. I have heard the gpu will take more from the pcie slot if it needs to so am I safe to put any gpu in it considering I already have the power connector and an adequate power supply

 

[Math Geek]

what motherboard says the pcie slot is limited to 35w? should be 70-75w as is the standard.

 

[InvalidError]

PCIe slots come in low (mainly x1/x4 slots) and high power specs (mainly x8/x16 slots) and the high power spec allows up to 75W.

 

[Amaides]

O sorry I am talking about oem motherboards that come from dell.

 

[Math Geek]

could you share what model and a link to where you saw it only gives 35w? i've not heard of anyone not following the standard for the slot which is 75w. i have upgraded many dell pc's before and not had any issues with any gpu so long as the psu could support it.

so would love to see exactly what/where you see this piece of info so can look further into it.

this is very odd so of course you've peaked my curiosity

 

[Amaides]

It is the dell optiplex 790 and on the spec sheet on page 19 download here
http://clascsg.uconn.edu/download/specs/O790.pdf
It says the pcie x16 has a maximum of 35w

 

[Math Geek]

looking the specs over i think i have an idea what is going on. the mobo has the Q65 express chipset on it. according to intel's spec sheet for it, there is only support for x1, x2 and x4 pcie 2.0. with a max of 8 pcie lanes total. so the x16 slot is really not a x16 slot and therefore did not get the full x16 power supplied to it.

http://ark.intel.com/products/52811/Intel-Q65-Express-Chipset

i would guess it is at best a x4 slot and therefore was only supplied with the lower power needs of an x4 slot. if you look on page 29, it lists the hd 6350 gpu you could get with the pc as a max of 20w. this may also be a reason why the slot did not get full power as they never sold it with a gpu that needed it. pre-built systems are notoriously proprietary and often put non-standard connections and other stuff into their pc's. i've never seen one with non-standard power limits but i am not entirely surprised to discover it here.

so to answer you're original question i'd do some heavy research before buying any gpu for the system. what you want to look at is how much of the power comes from the slot and how much from the psu. many of the brands/models use very little from the pcie slot and others rely more heavily on it. you just want to be sure that whatever you get uses minimal slot power and relies on the psu for almost all the power. tom's has been including this info since last year. the reviews they have done are a good source for this type of info. i don't recall off the top of my head what used what, but i'm sure you have an idea what gpu you're thinking of and can start there while searching the site's reviews.