Was reading through this Haswell OC guide posted at OCF and ran across what I thought were some interesting observations and I was wondering if you guys that have already had a chance to play with Haswell have come to the same conclusion(s).
The discussion point(s) in bold:
With Haswell, that has all changed. Memory is a strange beast with Haswell. With your CPU clocked at stock, the Haswell IMC is a beast. Some chips will be able to do DDR3-3000+ without so much as batting an eye. Others not so much, but DDR3-2400 isn’t a stretch at all.
But – and this is a big, bold, italicized, very notable but - overclocking a Haswell CPU at the same time as overclocking the RAM will reduce your IMC’s ability to overclock or reduce your CPU’s ability to overclock. You have to choose one or the other,
which is why the CPU came first in this guide. Core speed is king; remember that. If it comes down to choosing which to push farther, the CPU should always win in your calculations.
This will not only be heavily depending on the particular CPU you get, but also on the motherboard you choose. For instance, the Intel motherboard used for the Haswell review couldn’t run greater than DDR3-2133 at 4.8 GHz. However, using the same chip and the same memory, the ASUS Maximus VI Extreme for a future review had no problem running DDR3-2600 at 4.8 GHz.Speaking of ASUS, let’s start with an example they gave. You might be able to run DDR3-2800 RAM and overclock your i7 4770K to 4.4 GHz. However, drop that down to DDR3-1600 or DDR3-1866 and that same CPU at the same voltage might be able to get to 4.6 GHz now. Everything in Haswell is linked. Reducing RAM speed on poor-to-pretty good chips will almost invariably increase the CPU’s ability to overclock.
Thus, you know all these high speed kits that were selling well with Ivy Bridge? Get ready to see how tight they can tighten their timings at lower speeds. Timings are back folks. No longer can IC manufacturers count on increasing memory clock, timings be damned. If you can get your hands on an older PSC or BBSE based kit with tighter timings
(the G.Skill Flare DDR3-2000, 7-9-7-24 kit of yesteryear comes to mind. *Cough* someone killed mine…*cough* IMOG *cough*….), it would behoove you to do so.
So, have you needed to dial down the CPU in order to hit the highest memory clocks...and the reverse for highest CPU clocks?