I know this forum is largely Intel based so maybe this little problem may have passed allot of people by so I thought I'd run it by some folk. The Piledriver benchmarks are a fair bit improved over the Bulldozers and with the FX6300 seeming to be the pick of the bunch with value/performance I decided I would get one to have a gander at. Can never have too many computers right? First AMD CPU I have bought since a brief spell with a X6 1060T which was a miserable overclocker. Also picked up cheap and cheerful motherboard, a Gigabyte 78LMT-USB3. http://www.gigabyte.com/products/product-page.aspx?pid=4305#ov Has mosfet cooling and Gigabyte boards have always had a decent rep for solid caps and decent quality mosfets despite its 4+1 phases it looked fine for a 95w CPU. Only thing of note is i ditched the stock cooler and used a 120mm xigmatek cooler I had around, the direct heatpipe style which cools pretty well in fairness. So fired it all together and downloaded intel burn test and loaded cpu z to see what boost was doing to the CPU frequency. This is where it got a bit Every 2 or 3 seconds the CPU would go from its stock frequency of 3.5Ghz at full load 200 x 17.5 and drop back down to 3Ghz dropping the multi to 15. So under heavily threaded load situations my 3.5GHz would underclock itself, awesome! Had a play in bios disabled cool and quiet and the other energy saving bits and bobs and tried it all again and it still throttled. At stock speeds. It is also worth noting that everything was ice cold, temps on the cpu high 30's and the mosfet cooler had a fan over it and too was ice cold. Turns out this little issue is largely down to a feature called APM (advanced power management), something that very few Gigabyte motherboards give you the option to turn off. Mine doesn't and some higher end boards also suffer the same problem bar some beta bios that have been floating around so it isnt just a problem to lower end boards. This same issue is also rife on Asrock boards low and high end. So I am left scratching my head as to what to do now. It seems the only way to get round this issue is by sticking your Piledriver chip in something like a Sabretooth which is fine but its 3 times the cost of a standard motherboard and for this test i was only wanting to run STOCK speeds As I have various Intel systems with low end Gigabyte boards (check my sig) I find this a bizarre situation to find users in, motherboards that wont even run stock speeds. Especially as none of my intel boards have any form of mosfet/vrm cooling Is this to do with the CPU design or just motherboard manufacturers cheaping out? Because its definitely at a detriment to AMDs sales if motherboards cant even run it at stock speeds in threaded situations that the FX line is marketed for?
I ran into the same issue on my FX 8120, traced it back to APM - The point of it, so far as I can see, is to preserve the Thermal Limit on the FX chips, which is a bit thick - Why build a Chip with Turbo, then have it downclock under max load, even if it's got far more cooling than needed to keep it in check? It's a feature I feel that needs fixing, or at least made to rely on Temperature, rather than just load. I do agree with it being a bit thick that lower-end boards won't let you disable it, however. I don't understand why such a thing would be missing, then again, Gigabyte boards also lack LLC on AMD chips. Another thing to note is that APM is also indiscriminate. If over half the cores are loaded, so far as I experimented; it would immediately cut speeds. Which also accounts, in part, for Bulldozer and Piledriver looking awful in stock benchmarks - APM would throttle any attempting to use all cores. Yet again; AMD have looked at their feet and carefully chosen which one to blow a hole in.
Hey. Hows the Formula in regards this problem? Is clocking on the top end Asus boards fairly straight forward? Its possible I could stretch to the Sabretooth but not the forumula...
Try running prime 95 or intel burn test and run cpu-z at the same time. Could be the bios you have isn't a issue., defo reports of that board throttling.
The Crosshair V has settings regarding APM. By default it's enabled, which means the downclocking issues remain, but you can disable or dial back APM. I've not bothered investigating what difference dialling it back makes, simply disabled it and went on my merry way.
