10gbase-t running at 2.5g less heat?

[Greg_E]

If I were to buy a few of the cheaper 30 meter 10gbase-t SFP modules, would they run cooler if only using 2.5g connections? I have a bunch of 2.5g cards in my lab, and it would be nice to get some 2.5g modules for my switches, but the price of good 10gbase-t modules is a lot, and buying 2.5g dedicated modules seems self limiting (and still a lot of money). I need like 8 to 10 of these modules.

Might be cheaper to buy a no name 2.5g switch.

 

[jmsq]

I’d expect not; they get super hot even with nothing plugged in. I’d look for 2.5g SFP modules and compatible switches if you really want to go that route, but native 2.5gbt switches are probably a better bet since they’re so cheap with 10g SFP uplinks.

 

[kapone]

30 meter 10gbase-t SFP modules

I had two of those plugged into my firewall NIC (Intel X710), and they did get a lil toasty, but I don't worry about it. It is what it is. If they/or the NIC fails (and they didn't, ran for over 3 years in that toasty state ), I'll tackle it then.

There's only so much you can worry about.

 

[tgl]

I believe that a good deal of the complexity (and hence heat dissipation) of SFP+-to-RJ45 adapters comes exactly from the need to buffer different speeds between the 10G-and-nothing-else SFP+ side and the potentially-multispeed ethernet side. From that standpoint, feeding a 2.5G ethernet device is the worst case and hence likely to incur more not less power consumption.

As already said, a cheap 2.5G switch with a 10G uplink port or two would be a lot better answer. It's doing largely the same thing as those adapters, but with more thermal wiggle room and less need for bleeding-edge parts.

 

[blunden]

I believe that a good deal of the complexity (and hence heat dissipation) of SFP+-to-RJ45 adapters comes exactly from the need to buffer different speeds between the 10G-and-nothing-else SFP+ side and the potentially-multispeed ethernet side. From that standpoint, feeding a 2.5G ethernet device is the worst case and hence likely to incur more not less power consumption.

As already said, a cheap 2.5G switch with a 10G uplink port or two would be a lot better answer. It's doing largely the same thing as those adapters, but with more thermal wiggle room and less need for bleeding-edge parts.

The signaling required to get 10 Gbps over twisted pair with a decent signal to noise ratio over a longer distance is pretty complex from what I've read. I still think that's the majority of the reason for why they get hot.

 

[Greg_E]

My 10g twisted pair gets really hot connected to my 10g nas. I did put a little heatsink on it, and it helps a lot, but not something I want to do on a regular basis. The run in this case is around 5 feet on good 6a shielded cable. The 2.5g stuff would be around the same length.

I guess for now I'll just stay with gigabit on those adapters.

 

[louie1961]

If I were to buy a few of the cheaper 30 meter 10gbase-t SFP modules, would they run cooler if only using 2.5g connections?

In my experience, no, definitely not.

 

[olafotioup]

Hello,

XICOM 10GBase-T SFP+ to RJ-45
XICOM SFP 10G SR SFP+ Multimode Duplex LC

I use these connectors for both 2.5G and 10G and there is no temperature difference, +/- 56 degrees on average.

 

[Greg_E]

Thanks, I'll look into the XICOM brand and see what I can find.

 

[jamesdwi]

if at all possible avoid 10gbaseT, I have a Mac Studio with a 10gig copper port, burned out my first tranciever on it, barely any use at the time, just stopped working. Currently I have a 120mm fan that came with a USB adapter pointing at the tranciever with little heatsinks on it top and bottom, not sure if the fan is needed, because it was cheaper just to stick on some heatsinks and buy the fans off ebay for $20 and have it run cool to the touch.

For any device that had an option to get a sfp+ nic, and switch is my first choice, DACs are about the same price and run cool even have 40gig DAC and 100gig DAC with break out cables that are cool to the touch.

 

[blunden]

For any device that had an option to get a sfp+ nic, and switch is my first choice, DACs are about the same price and run cool even have 40gig DAC and 100gig DAC with break out cables that are cool to the touch.

I agree that DACs or fiber are preferred for 10 Gbps. Sometimes that's not an option though, which is why more efficient transceivers are important.

You can sometimes get DACs for dirt cheap on AliExpress. My latest 2 meter 10 Gbps DAC from ONTi cost me $3.12 including 25% VAT after a significant coin discount.

If we're talking passive DACs, those don't generate any heat on their own.

 

[jamesdwi]

I agree that DACs or fiber are preferred for 10 Gbps. Sometimes that's not an option though, which is why more efficient transceivers are important.

You can sometimes get DACs for dirt cheap on AliExpress. My latest 2 meter 10 Gbps DAC from ONTi cost me $3.12 including 25% VAT after a significant coin discount.

If we're talking passive DACs, those don't generate any heat on their own.

agreed, the china vendors are a great deal, but shipping also takes a great deal of time, or a great deal of money. Currently waiting for full height brackets for a pair of 100gig nics, I got cheap off ebay, but didn't notice they only came with low profile brackets. US sellers wanted $30 for a bracket, from china I am getting 5x brackets for less than the US sellers wanted for one, which was about 1/2 the price the card were on ebay.

 

[blunden]

agreed, the china vendors are a great deal, but shipping also takes a great deal of time, or a great deal of money. Currently waiting for full height brackets for a pair of 100gig nics, I got cheap off ebay, but didn't notice they only came with low profile brackets. US sellers wanted $30 for a bracket, from china I am getting 5x brackets for less than the US sellers wanted for one, which was about 1/2 the price the card were on ebay.

Indeed. It only took 10 business days in my case, so not too bad. Shipping was free.

$30 is definitely a bit too much.

 

[nabsltd]

$30 is definitely a bit too much.

In the US, you can get a 2m 10Gbit DAC for $10-15 from Amazon. The advantage would be being able to return one that didn't work.

But, at less than $5, you could just buy 3 and throw one away if it doesn't work.

 

[blunden]

In the US, you can get a 2m 10Gbit DAC for $10-15 from Amazon. The advantage would be being able to return one that didn't work.

But, at less than $5, you could just buy 3 and throw one away if it doesn't work.

Pricing is a little higher here, and you'll also have to include the shipping cost in the comparison as well. The price I paid was probably roughly half the shipping cost, at most.

This was an extreme example though, as the normal price was roughly $12.4. The AliExpress coin discount was just unusually high in this case.

 

[Greg_E]

In the US, 10Gtek DAC cables are pretty cheap. Multimode OM-4 jumpers are really cheap. But my NAS has a 10g copper port, and I'd like to feed some of my 2.5 g a+e cards into my faster switches if I could find good and cheap sfp+ modules. It's getting to the point where the cheapest option for this design is the 30 meter 10g modules and try to deal with the heat.

I have found that for my NAS, the module in my switch responds well to a little 14x14mm heatsink glued to the exterior part of the module. Still runs hotter than I want, but better. I really need to invest in a higher quality, newer design module that runs at lower temperatures.

 

[blunden]

In the US, 10Gtek DAC cables are pretty cheap. Multimode OM-4 jumpers are really cheap. But my NAS has a 10g copper port, and I'd like to feed some of my 2.5 g a+e cards into my faster switches if I could find good and cheap sfp+ modules. It's getting to the point where the cheapest option for this design is the 30 meter 10g modules and try to deal with the heat.

I have found that for my NAS, the module in my switch responds well to a little 14x14mm heatsink glued to the exterior part of the module. Still runs hotter than I want, but better. I really need to invest in a higher quality, newer design module that runs at lower temperatures.

The Wiitek ones might still be somewhat reasonably priced on Amazon since it ships from the US. I don't remember what speeds they support though.

EDIT: Apparently they switched the PHYs in the newest revision of the Wiitek transceivers apparently.

How have you connected things at the moment? Sometimes it's better to just get ones of those dirt cheap 4 * 2.5 Gbps RJ45 + 2 * SFP+ switches in order to minimize the number of 10GBASE-T transceivers if you have a few 2.5GBASE-T devices you want to connect to an SFP+ switch.