Up until recently, overclockers pushing their CPUs past 250FSB would have to lower their memory ratios in order to maintain stability. Whether it'd be 5:4, 3:2, chances are, you wouldn't be able to run it 1:1. As many enthusiasts know, the best performance will come with your memory running in sync with the CPU, thus the introduction of PC4000 ram.
Add to the mix that the standard for enthusiasts, be it AMD or Intel, are Dual Channel motherboards. We take a look at the newest matched pair from OCZ, which is a couple of sticks of their PC4000 Gold series ram.
ULN Technology: (U)ltra (L)ow (N)oise shielded PCB
512MB (2x256) and 1024MB (2x512) kits based on OCZ brand EL DDR IC
Featuring OCZ HyperSpeed® technology for outrageous top end speeds*
Optimized for High Speed applications on Intel i865/i875 chipsets
500Mhz CL 2.5-4-4-7*
EVP®(Extended Voltage Protection) Technology allowing up to 3.0 volts VDIMM while maintaining full warranty **
184 Pin Dimm
OCZ EL DDR PC4000 Gold Dual Channel Kit
OCZ's packaging has changed since we've last looked at their OCZ EL DDR PC3200 Dual Channel Platinum. Rather than two individually packaged ram modules, we now got both of them in the same package. This of course doesn't really mean much, but it does make it clearer that this kit is a matched pair.
A cosmetic change from before, their ram is encased in gold heatspreaders. I'm preaching to the choir here, but heatspreaders have yet to convince me that they effectively cool ram to the point where it will make a difference in overclocking. They do look swank though, and I guess any cooling included won't hurt. Like before, the heatspreaders are attached to the ram via some frag tape. Not the ideal choice if cooling really matters, but it is less costly than individually applying thermal epoxy at the factory.
Not much information is given on the labels. Other than the ram speed, you're given the memory size and the product series. Missing are the ram timings, but according to specifications, they are 2.5-4-4-7, which is very impressive. Standard fare for PC4000 ram is normally 3-4-4-8. Naturally, we'll test the ram's ability to be tweaked.
Given our past success overclocking OCZ products, I had some high hopes for the Gold PC4000. Keeping Memtest86 handy for stability testing, we first tested the ram at 200MHz (400DDR) since all current Dual Channel motherboards, AMD or Intel support this speed. The reported SPD was 3-4-4-8, so we started pushing the memory timings until we settled on 2-3-3-5. The ram did POST at 2-2-3-5, but we hard locked once we entered Windows.
Next step was 250MHz. Reported SPD timings were 3-4-4-8, so naturally, we weren't going to stay there. We adjusted them to the rated 2.5-4-4-7... all was good. We got as low as 2.5-3-3-6, and the system successfully booted into Windows. This was something we weren't able to achieve with our Corsair TWINX1024-4000, but before we celebrated too much, the system crashed once we fired up SiSoft Sandra. We pushed the voltages from 2.8v to 2.9v, but we witnessed the same instability. We didn't have to fire up Memtest to conclude that the ram wasn't able to handle these timings. Moving down to 2.5-4-3-6 was met with better results. We then relaxed the timings back to 3-4-4-8, and went for our maximum OC.
280FSB, which works out to 560MHz is quite impressive. Easily the highest overclock of any ram we've tested, let's move on and see if the performance is reflected the same way.
Just to clear something up, our 2.4C can do in excess of 300FSB using a 5:4 ratio, but that isn't the point here. We are trying to test for the maximum memory OC, and our board does not offer options where the memory can run faster than the CPU FSB. So to clarify, why at 1:1? The memory won't reach it's OC limit at 5/4, in "most" cases as your CPU will probably top out in the 300 range. This isn't set in stone, as every CPU is different. Now, assume the CPU can hit 300. You use 5/4. Your ram will max out at 260. However, the memory can do more.
Asus P4C800-E: Pentium 4 2.4C, 2 x 512MB OCZ EL DDR PC4000 Gold, ATI AIW Radeon 9700 Pro, 80GB Western Digital, Windows XP SP1, ATI Catalyst 3.5.
Test Software for both platforms will be:
Unreal Tournament 2003
Comparison ram will be some Corsair TWINX1024-4000. We will be presenting benchmarks at 200FSB @ 2-3-3-5, 250FSB @ 2.5-4-3-6, and the maximum OC on the P4C800-E @ 3-4-4-8, all in Dual Channel mode.