Bitcoin Forum

So my Sapphire 5850 is currently at 725 Mhz and recently bought
Is it worth to overclock it now?
And how much would be the overclock with those?
Thanks

Should be able to get near 900,300 core/memory at 1v or at least that is what the ones I have are able to do for around 360-370mh/s.

How long have you been using them?

I'm afraid that if I overclock them, they won't last the same as normal

Using them in this way to mine is going to do the same anyways the cards are not designed to do 100% load 24/7 as it is, that said my 5830s until I took them out of service recently worked fine for 11 months two fans died out of about ten cards but other than that no problems.

thanks for the info, will oc them a bit

If you wanna be conservative with them ... just clock them at 840/300 and you will get a good 340mhash.

I myself run an Asus 5850 as a 24/7 miner. It actually runs at stock voltage at 920 mhz 24/7. It does have a Zalman VF-3000 (I think that's what it is) aftermarket heatsink on it so it stays cool.

How far you're going to be able to overclock it depends on both the lottery of silicon quality and how good the fan is. Make sure you don't exceed 85 celsius on either the core or the VRM.

Overvolting will increase heat output a lot faster than just increasing the clock frequency. I can push mine all the way to 980 with overvolting but I don't because it gets too hot to run safely (in my opinion).

As others have said you're pushing the card more than it's designed to anyway with mining so in my opinion you may as well overclock. I personally would increase in 10 mhz increments and then run the miner non stop for 24-36 hrs. If you have no problems push it another 10 until you hit a wall where it won't go any further. At that point you've either reached the limit of your card or you need more voltage. Whether you want to overvolt is up to you, but don't push it higher than 1.3 volts on the core. Again, make sure that you have adequate cooling and stay below 85c on the card components.

Also keep in mind that throwing more voltage at the card tends to make it less efficient, which is another reason why I've got mine to my stock voltage limit of 920 and don't try to go further. You can reduce your VRAM clocks to 300 mhz and that should save you a little power without impacting your hashrate (saves about 15-20 watts on mine).

nice answer thanks

My advice is to undervolt a bit, then try and find your most stable overclock.

That way your still in the same TDP window.

There are quite a few good posts about undervolting/overclocking in the hardware forum :

This is a good thread with a chart at the start for ppls max - https://bitcointalk.org/index.php?topic=65971.0
If you read through the thread you will notice that quite a few ppl overclock and undervolt to help maintain temps and power consumption levels.

Good thread about efficiency gained by undervolting - https://bitcointalk.org/index.php?topic=76115.0

Another thread specific to the 5850 - https://bitcointalk.org/index.php?topic=70095.0

Search option with '5850 overclock' as the parameter - https://bitcointalk.org/index.php?action=search2

While most of these threads are about undervolting, the same applies to overclocking, you find the max clock before errors at a specific voltage.
You either up your voltage (for an overclock) until you attain a clock spead / temp ceiling or in the case of an undervolt, you drop your core speed until it works at the specific voltage.

kind regards

Also running 4 pieces 900/300 for 10 month now.. all ok..

so my aircooled newbies ...
with biosupgrade and watercoolerblock nearly no limit
btw 1070/300 1.25v  440M/hash
and warning for youself don't do it whitout a waterblock

Yeah and damaged hardware from a Waterleak is pretty cool too.

http://666kb.com/i/c40uiumkn09pw2l0h.jpg

did you know that ... its called distilled water and Corrosion protection additives

http://all-funny.info/wp-content/uploads/2010/01/watercoolingfail.jpg

Oh special way of watercooling.  8)
No sry, never ever will put water inside a pc. Dont care about fancy hoses, shiny coolblocks and blue green white red water ingredients.
But if you like than do so. I am very conservative on this.  ;)

^This. Undervolting makes a big difference on power, but also on Temps! I brought my 5850 to .95V, and noticed significantly lower temps.