Power is your biggest enemy with these extender/risers. We're actually in the middle of designing our own, and it's a struggle to get all 75w from the board to the card without "burning up" wires. Typically the ribbons are 28-32 awg, which can handle about 0.142 A each. Depending on the vendor/manufacturer/designer of the riser, there are 1-5 power leads.<br>

Assuming they use all 5 leads - doing the quick math...<br><br>

12 V - 5wires X 0.142 A = ~0.71 A = ~ 9 watts<br>

3.3 V - 5wires X 0.142 A = ~0.71 A = ~ 2.5 watts<br><br>

Keep in mind these are "open air" and very conservative estimates. But a good rule of thumb <img alt="smile.gif" class="bbcode_smiley" src="http://files.overclock.net/images/smilies/smile.gif"><br>

Active cooling will help with overhead. Decent, indoor (cooler) temperatures will also help.<br><br>

This is why you'll see a lot of those risers come with Molex, P4, mini-fit Jr, etc, power connectors to supplement. Often times if your card has external power (like most PoE or Video cards do) you'll be fine.<br><br>

This thread was very valuable for our research during the design process. Great reassurance that we won't have to worry as much about throughput & interference with longer cables. Regardless, we plan to shield with foil tape, just to be safe ;-)<br>

Cheers!