I currently have one 7850 in my build as in my sig below, but in light of the anticipated delay if 8 series cards I am interested in buying another 7850 and running a crossfire arrangement. Firstly, are there any massive problems/issues know running a crossfire setup? I did a bit of research and the bit tech article is dated 2005 I found. Any other internet snippits with issues seem to be from a while ago too. I may be looking in the wrong place though as my google foo is not strong Secondly, would I need to buy a new PSU to accommodate the second card? I have a corsair 650 as below Thirdly I suppose, do you think it's worth it? I'm really intrigued by different options/solutions etc.... for playing around with so just after some advice. Cheers
http://forums.bit-tech.net/showthread.php?t=243582&highlight=microstuttering have a read all about `micro stuttering`
Thanks for linking to that Harlequin - it's a good read. I'm not totally put off as there seems to be some hope that gaming at 1080p (which I do ) is ok? For example it's highlighted that using 2 cards that when on their own are not running slow seem to not suffer the micro shuttering problem as much. Interesting. I'm afraid I can't extract the parts easily from the thread as I'm not on the PC at the moment. I would still be very interested in hearing other people experiences though.
You would have to measure from wall to see if you need a new psu. If its above 400watts single card your looking 600+ for crossfire which is borderline long term on that psu. Would like more headroom if it was me. Personally I'd look to sell the 7850 and buy a 7970. Performance is similar without the issues.
There was a thread a few days ago where somebody had measured the power consumption of his dual GTX480 system IIRC, and it was around 600W. The system in my sig pulls around 330W from the wall on full load. I think your 650W unit would be fine. You could get a power meter to be sure though.
Thanks for the reply rollo and mm vr, I might pick up a power meter and give it a test to see if I will have enough headroom. This thread is interesting - based on tri 7970s Point taken about selling the 7850 and going for a 7950 but for some reason I seem interested in CF set up! If anyone else is running crossfire setup I would be interested to hear.
Current 13.2 Beta 5 drivers have reduced frame times to reduce such micro shuttering in CFX. (Just took longer for AMD to realize there was a problem, and now that they have been more devoted in tweaking their drivers, they have yielded great results. Better than ATi who would just chuck out rehashes of drivers every month.) So times have changed for the better.
Thanks TG, I had only updated to throw beta 4 drivers whilst playing Cryais 3 open MP beta, and now that's finished I had not looked at new driver. It's good to know that AMD are actively looking for solutions. Looks like I just need to figure out if my current PSU will support another card with sufficient headroom and I might take the plunge: )
Right so I bought myself a electricity plug in monitor jobbie as people had suggested. I have run the monitor with the max watt setting with both Crysis 3 in Multiplayer with most settings on high, 2xsmaa and 16 AA. Addiitonally I ran the new 3DMark benchmark too. Both ran with the rig as per my sig. Whilst running both individually the result never went over 240.6Watts as below Does this seem right? I was suprised how low it seemed! With this in mind and a 650w PSU, do you think I have enough headroom to add another 7850? If I doubled the 240W draw for the whole system (unlikely for the addition of a single card to the system?) this would give circa 500W, so 150W head room. Let me know if my thinking/ readings seem wrong please! Cheers
Well thats positive Thanks PSU is Corsair TXM 650W Modular PSU as seen here; http://www.ebuyer.com/279547-corsair-txm-650w-modular-psu-cp-9020002-uk
That's a good PSU. With a second card, you'll hit the top of it's efficiency curve, right around 50%.
Until about 5 mins ago I had no idea what you meant but i can now only assume you are refering to the below or similar. Do you mean that with another card my PC will be at apx 50% load (in games etc...) which will in turn mean the PSU will be running at circa 80% efficiency? Thx for help
Yes, with a second card, your PSU will run with about 50% load, which is where it's most efficient (above 85%).
Sounds about right. Computers don't pull as much as many people think. You can reach more than 400W only with dual graphics cards really.
Cheers mm vr - looks like im going to take the plunge This post on tomshardware seems to clarify also http://www.tomshardware.co.uk/forum/340021-10-sapphire-7850-crossfire-corsair-650w
Right as I have had such fantastic advice up till now, I tought I would be cheeky and ask for some more! So, I am about to buy another 7850 as above and in preparation for this I thought I would rearrange some bits of kit to achieve the optiumum space. Essentially this has meant moving the sound ard from the bottom PCI 1x slot to the top, above the current GPU. As per the photo below, I now propose that I site the second GPU below. This in turn means that there will be about 20mm between the bottom of the top card's housing and the top of the second cards PCB. In light of this, I assume air flow will be affected! So, what do you advise on the best cooling set up with this in mind? I currently have 1 intake fan in front of case and 1 exhause in top. Additionally my CPU cooler is push/ pull through the rear. The case has space for 1 more front fan, 1 side pane fan and 1 floor fan. There is space for another top fan, but unless it is really, really, really thin it wont fit as it will clash with the CPU cooler radiator. Fans are currently 120mm fractual jobbies. Apologies for the ramble! I would like to order any additional fans with my card. Cheers
Well you are lucky in that you have decent clearance between your two GPUs. If I were you I'd attach a decent 120mm to the side panel, that way it'll blow air straight into your GPU intakes, and also over the backplates. Fan wise, its up to you, the Gentle Typhoon 1450s move a shedload of air but there are quieter fans out there.
