PCI-E 2.0, what does it bring

[_33]

My X58 motherboard and my ATI Radeon HD 4850 both support PCI-E 2.0, but what does it bring? I can change the bus speed in the bios (currently set at default 100mhz), but I am unsure of the frequencies supported. I doubt raising the frequency would provide better framerates in gaming, but I'm curious as to what PCI-E 2.0 brings to the table(?)...

 

[FordGT90Concept]

It is double the bandwidth and I think it supports more voltage via the slot. 2.0 is backwards compatible with the original.

 

[LittleLizard]

It is double the bandwidth and I think it supports more voltage via the slot. 2.0 is backwards compatible with the original.

+1 but nothing more than that. really doesnt matter right now if u have or not 2.0 Unless u have a gtx 295 oced

 

[Error 404]

It also means that if your motherboard has a crossfire or SLI setup such as 16x, 8x, 8x, then the two 8x slots still give as much bandwidth as a PCI 1.1 x16 slot; since most graphics cards don't need more bandwidth than that, they should run fine.
Other than that, nothing new to the table.

 

[Mussels]

its only useful atm for the dual GPU video cards.

Its just future proofing.

 

[_33]

Lots of answers in a short period of time*. I thank you all
I've asked that question out of curiosity, because I remember when PCI-E 2.0 came out, there was talk about possibility of overclocking the bus up to 150mhz and that the ATI cards can take the frequency, as well as the new Nvidia chipset (that was after the NF4). Now since I have a X58 (not an NF4), I kind of was tempted to try it but tought the extra bandwidth of an overclock of the bus is probably useless. Anyhow...

 

[LittleLizard]

1-The extra bandwith isnt necessary at this point of time. If your slot works at 4x instead of 16, then maybe but never put it so high or your northbridge wouldn't handle it.

2-Safe limit = 115, 120 if you feel like exploding things.

 

[largon]

As an interesting sidenote, OC'ing PCIe 2.0 from "100MHz" to "110MHz" raises the actual link frequency from 2.5GHz to 2.75GHz. The PCIe frequency you see in BIOS is just a reference freq of a sort, the real physical frequency running in the slots is generated by multiplying the reference freq by ×25. Say hello to miracles of differential clocking.

Btw, speaking of diff. clks, GDDR5 will move to differential clocking within about a year. Meaning video memory bandwidths are going to double over what current (that is, single-ended) GDDR5 offers now.

 

[mastrdrver]

its only useful atm for the dual GPU video cards.

I moved from a PCIe 1.1 board to a PCIe 2.0 board and saw a gain in performance of absolute zero for my 4870x2 in actual game play. Cod 4/WaW, Burnout, Cysis demo, and GTA IV and there was no difference between the new board and old. I play all those games at 1920x1200 also with as much AA as I can throw at it.

I too did all the looking at benchmarks and still wasn't sure that I wouldn't lose anything by going with a P45 vs a X48 board. In the end I'm happy I went with the P45 board.

 

[Mussels]

I moved from a PCIe 1.1 board to a PCIe 2.0 board and saw a gain in performance of absolute zero for my 4870x2 in actual game play. Cod 4/WaW, Burnout, Cysis demo, and GTA IV and there was no difference between the new board and old. I play all those games at 1920x1200 also with as much AA as I can throw at it.

I too did all the looking at benchmarks and still wasn't sure that I wouldn't lose anything by going with a P45 vs a X48 board. In the end I'm happy I went with the P45 board.

by useful, i didnt mean on a 16x slot. If you're crossfiring them you have 2 8x slots on most boards - and with 4x bandwidth to each GPU you'd really be hoping they're 2.0 slots

 

[mastrdrver]

I understand. My point was that I went from the equivalent of pci-e 2.0 8x (pci-e 1.1 16x) to 16x and didn't see any performance change at all.

 

[Mussels]

I understand. My point was that I went from the equivalent of pci-e 2.0 8x (pci-e 1.1 16x) to 16x and didn't see any performance change at all.

yep. i went from 1.1 crossfire with a 4x slot to dual 16x 2.0 slots and had barely any difference. an 8x 1.1 slot is enough for just about anything.

 

[BradleyKZN]

Its very comforting to know!

 

[hat]

double the max available bandwidth and double the wattage. 8GB/s instead of 4GB/s. 150w instead of 75w.

 

[mastrdrver]

double the max available bandwidth and double the wattage. 8GB/s instead of 4GB/s. 150w instead of 75w.

I think the most important spec out of all of it is the increase in wattage through the slot. Unfortunately, that is the max that the spec is for and the board is not required to deliver that power level for 2.0 spec.

 

[Hayder_Master]

the pci-e bandwidth speed is 5Ghz , no card right know have this speed and have this size of bandwidth even the 4870x2 and gtx295 booth of them not reach 4Ghz yet , only ATI plan to active the bridge between the two cpu's in 4870x2 with they say this way maybe hit the 5Ghz speed bandwidth and that's mean full pci-e 2.0 bandwidth , also the 5Ghz for pci-e not the maximum speed , in fact with overclocking expect go over 6Ghz
at last the card's run at pci-e 2.0 version but no card use the whole bandwidth yet

 

[largon]

double the max available bandwidth and double the wattage. 8GB/s instead of 4GB/s. 150w instead of 75w.

I think the most important spec out of all of it is the increase in wattage through the slot.

Rated slot wattage is a moot point since pretty much no card out there exceeds even 75W draw from the slot.

the pci-e bandwidth speed is 5Ghz , no card right know have this speed and have this size of bandwidth even the 4870x2 and gtx295 booth of them not reach 4Ghz yet , only ATI plan to active the bridge between the two cpu's in 4870x2 with they say this way maybe hit the 5Ghz speed bandwidth and that's mean full pci-e 2.0 bandwidth , also the 5Ghz for pci-e not the maximum speed , in fact with overclocking expect go over 6Ghz
at last the card's run at pci-e 2.0 version but no card use the whole bandwidth yet

Say, what?

 

[FordGT90Concept]

Rated slot wattage is a moot point since pretty much no card out there exceeds even 75W draw from the slot.

It wouldn't be stable if it did. Usually card manufacturers try to have about 30% more power available than the maximum the card could draw. For instance, the Radeon 4890 is a 190w card but it has two 6-pin power connectors (6 * 25w = 150w) on top of the 75w provided by the PCIE x16 slot. The card has 225w available to it even though it will never draw that much.


The closer you get to the electrical limit of the circuits, the less reliable it becomes.

 

[Hayder_Master]

http://largon.wippiespace.com/smilies/blankstare.gif
Say, what?

ok , seems im go far but im was want to explain so i want say
1-pci-e 1.0 =2.5Ghz bandwidth
2-pci-e 1.1= up tp 3.5Ghz
3-pci-e 2.0= 5Ghz
but this is pci-e mobo bandwidth not the card's , so i mean in fact right now no craphic card use this much of bandwidth , so the 4850 run at same performance run at pci-e 1.1 or 2.0 not sure about same performance at 1.0 maybe 5% less performance

 

[mastrdrver]

It wouldn't be stable if it did. Usually card manufacturers try to have about 30% more power available than the maximum the card could draw. For instance, the Radeon 4890 is a 190w card but it has two 6-pin power connectors (6 * 25w = 150w) on top of the 75w provided by the PCIE x16 slot. The card has 225w available to it even though it will never draw that much.


The closer you get to the electrical limit of the circuits, the less reliable it becomes.

That's kind of the point I was trying to get at that since the spec is higher for 2.0, lower wattage external connectors should be needed to be "in the ballpark".

 

[phanbuey]

I understand. My point was that I went from the equivalent of pci-e 2.0 8x (pci-e 1.1 16x) to 16x and didn't see any performance change at all.

In order to REALLY see a big change from 8x to 16x you need to use tons of AA and AF and run out of Framebuffer - the 8gb/s vs 4GB/s makes very, very little difference for current gen vid cards. They did tests on a 9800GX2 (512 MBx2) card and only when the GPU's ran out of frame buffer which caused massive texture swapping across the bus did the performance decline.

here is the article http://www.tomshardware.com/reviews/pci-express-2.0,1915-12.html

 

[AllHopeIsGone1]

Yeah, you don't wanna mess with the PCI frequency. It can damage the card/slot.

 

[Tatty_Two]

double the max available bandwidth and double the wattage. 8GB/s instead of 4GB/s. 150w instead of 75w.

5Gbit intstead of 2.5GBit

 

[OnBoard]

Was thinking would I lose performance, but good that I wont.

I stuck a 8500GT to my other slot and it's (card) PCI-E 1.0. Thought I'd get something like 16x and 4x as they are not in crossfire, but both dropped to 8x. Difference is that GTX 280 is PCI-E 2.0 8x and 8500GT PCI-E 1.0 8x.

The other card is there just for my LCD TV, so that I get 2D clocks to my GTX280. Don't really know if I lowered wattage with this config that much

 

[Tatty_Two]

Was thinking would I lose performance, but good that I wont.

I stuck a 8500GT to my other slot and it's (card) PCI-E 1.0. Thought I'd get something like 16x and 4x as they are not in crossfire, but both dropped to 8x. Difference is that GTX 280 is PCI-E 2.0 8x and 8500GT PCI-E 1.0 8x.

The other card is there just for my LCD TV, so that I get 2D clocks to my GTX280. Don't really know if I lowered wattage with this config that much

P45 is 8 x 8, P35 was 16 x 4, 8 x 8 is much better whether they be PCI-E 1.1 or 2.0.