Do you have an X99-based platform? Do you only need 16GB? Those easily-answered questions lead to a much harder one: which memory kit to you buy? An increasing assortment of reasonably-priced DDR4 makes it more difficult to pick the right one. Companies that were able to get into the market early and make a bundle of cash on overpriced parts have already done so, giving us a larger group of higher-volume products competing with substantially similar specs.
In other words, the DDR4 market is becoming a race for value.
Redline 994206F memory modules by Mushkin Enhanced are aimed at the middle of the DDR4 market, where performance enthusiasts trend when they want to put more cash towards the processor or graphics. How does a brand stand out in such a price-sensitive pocket?
Red heat spreaders help, as does a DDR4-2800 CAS 15 rating. Then again, you’re paying an extra $30 for that higher rating, compared to Mushkin’s own DDR4-2666 CAS 15. We’re probably going to need to settle this by overclocking!
In fact, you’re not going to get very far without overclocking, since DDR4-2133 CAS 15 to 19 are the only configuration options that don’t require tuning your CPU. Every motherboard we’ve seen configures a DDR4-2800 XMP profile by first selecting the processor's 1.25x BCLK strap (the internal ratio of the CPU core to the lower parts of the CPU, such as it PCIe 3.0 controller). Choosing this strap automatically overclocks the CPU by 25%. And, realizing that a 25% CPU overclock probably won’t work at stock CPU core voltage, motherboard vendors program their firmware to set a lower CPU multiplier. For the Core i7-5930K, it’s usually 30x.
The numbers get messier from there, as Intel rates the Core i7-5930K at 3.5-3.7GHz, depending on the type of load applied. But 30x125=3750. That fixed frequency interferes with certain low-power states and maintains a 50 to 250MHz advantage over the stock configuration. Enthusiasts might think this is great, but it’s not exactly fair to compare different memory kits at different CPU frequencies.
Automatic CPU overclocking doesn’t stop there, as 125x11x2 is 2750, not 2800. Our motherboard attempts to reach the memory’s full 2800 MT/s data rate by increasing the core BCLK from 125 to 127.3MHz. We now have a 3.82GHz CPU core, which is great for performance but, again, doesn’t allow a direct memory performance comparison.
Fortunately, our Asus X99-Pro sample supports data rates far above the 2666 MT/s available on most motherboards. Its 14x 100MHz memory ratio isn’t super-stable, but it is stable enough to operate this memory at its rated frequency. Crashes at 14x typically apply to memory that’s already nearing its limit, and it looks like Mushkin’s Redline 994206F has room to grow.
Speaking of growth, our collection of 16GB quad-channel memory has grown to the point that we may soon find ourselves forced to break these out by rated data rate. That’s a shame really, since we’ve seen so many lower-rated kits reach such high overclocks that they really should be allowed to run with the big boys.