Printed Circuit Boards Impact Performance


6 Kits, 5 Companies, 3 Colors, 1 IC Choice

The memory in your computer can make or break your attempts at overclocking. Recently while characterizing six low latency DDR1 PC-3200 memory kits we noticed a performance gap when overclocking the modules. Sure, it is not uncommon to experience a few MHz here and there, but we were seeing 20+ MHz differences from similar memory kits. The memory kits we have from Corsair, Kingston, Mushkin, OCZ, and PQI are pretty much identical. They all have models with identical latencies (2-2-2-5), some basic heat spreaders, Samsung TCCD IC's and a lifetime warranty. So, memory modules using identical IC's at identical latencies should yield similar results. We found that this was not the case and discovered a new bottleneck for memory -- the PCB. Sit back and grab a drink while we reveal the bottle neck to you so the dedicated enthusiast knows what is going on.

Identical IC's:

PQI - detail

Once I removed the heat spreaders I found that in all 6 kits the memory modules use Samsung TCCD Revision "F" Integrated Circuits (IC's). The full part number was K4H560838F-TCCD. All the modules used the same part number IC's. These IC's from Samsung are in the TSOP form factor and are rated by Samsung at 4ns. So, out of the tray, these Samsung TCCD IC's come rated at 500MHz, with relaxed timings of 3-4-4. Sure you will find some minor differences between batches, but that is not the case today. Let's look at the major difference for the memory kits that we used.

Different Printed Circuit Boards (PCB's):


PQI's Brain Power PCB (Top) Versus Corsair's Top Search Reference PCB (Bottom)

After taking a quick look at a couple of modules with the heat spreaders off, the differences in the PCB are very apparent. Corsair, Kingston, and Mushkin use boards that are based on the JEDEC reference design. OCZ Technologies and PQI use a different PCB made by a company called Brain Power, which is a Taiwan based corporation. Of the six kits we tested there were 3 types of PCB's used: The reference, Brain Power's, and Corsair's modified reference design for use with the Pro series. The three designs are shown below so you can see the differences on both sides of the modules. We didn't want to take the heat spreaders off of our pro modules (they are not taped) so we used one of the extra blank Corsair Pro PCB's that we had on the shelf.


Side A: Click to Enlarge


Side B: Click to Enlarge

Let's look at overclocking performance to see how these modules did.

Memory Performance

Our Test System:

Testing Procedure:

All testing was done on a fresh install of Windows XP Professional build 2600 with Service Pack 1A and DirectX 9.0b. All benchmarks were completed on the desktop with no other software programs running. No overclocking was done on the video card unless noted. Our testing processor was an unlocked Intel Pentium 4 3.2C. Our testing was done at:

The audio, USB, Firewire, and LAN features were disabled in the BIOS menu for all the testing completed during this review. All memory was set at the timings noted in the graphs. All testing was completed at 2.85Vdimm unless otherwise noted!

Tight Timing Testing

Results: At tight timings the modules all performed roughly the same no matter what PCB was being used. OCZ and PMI both use the Brain Power PCB's and are ranked first and last! All the reference PCB's are right in the middle of the pack. Nothing significant here so lets take a look at some different timings. It also doesn't look like the modified reference design hurts the Corsair XMS XL module either.

Moderate Timing Testing

Results: At CL2.5 timings we see that all the modules are able to run above 250MHz without throwing any errors during RST Pro2 testing. Note that the OCZ and PQI modules are now both leading the pack by at least 11MHz on the Front Side Bus (FSB) meaning an overall 22-30MHz gain in terms of DDR memory. The OCZ Platinum Revision 2 modules were able to run at DDR550 with aggressive CL2.5 timings. That is a 30MHz Brain Power PCB advantage over the closest reference designed PCB modules.

Loose Timing Testing

Results: Just like the prior graph we see that PQI and OCZ lead the group by a significant difference! The leading Brain Power PCB was 17-21 MHz faster than the other brands using the JEDEC reference design. Would you rather be running DDR564 or DDR522! We are talking about a 42MHz difference in performance from the leading kits from each design. Any overclocker knows that an additional 21MHz FSB and 44MHz on the memory makes a huge performance difference.

Conclusions


Height Difference


Trace Route Differences

Nathan Kirsch's Thoughts:

I never thought that that the PCB could be such a limiting factor for memory performance. Our results were so shocking that we contacted the memory companies' engineers to verify our test results. Corsair Memory's Application Specialists went through the same characteristic testing that we did and came up with the same conclusions. This verifies our test data and our hypothesis that the modules using Brain Power PCB's offer better high-end performance without sacrificing low-end performance levels.

We found that at tight timings (2-2-2-5) the difference in PCB's is minimal and insignificant. So, if you are not an enthusiast/overclocker then this article will not impact your buying decisions. If you are an overclocker looking to get the highest possible FSB/Memory performance at loose timings, then we just showed you a secret that can help you gain up to 42MHz on your memory overclock. The performance gain is great, but let's go ahead and look at pricing and see how much the OCZ and PQI memory kits cost.

Low Latency PC-3200 Pricing

Brand

PCB Type

Consumer Price

Price Per MHz

Live Pricing

Corsair XMS XL

Reference

$254
49 Cents (516MHz)

Corsair XMS XL Pro

Reference

$293
56 Cents (522MHz)

Kingston HyperX

Reference

$268
52 Cents (514MHz)

Mushkin Level 2

Reference

$288
55 Cents (520MHz)

OCZ Platinum Rev2

Alternative

$275
49 Cents (556MHz)

PQI Turbo

Alternative

$255
45 Cents (564MHz)

Not only do the PQI Turbo PC-3200 memory modules overclock the best they also cost the least! Now here is the kicker that I just have to throw out there. The Brain Power PCB's are one third the cost of the reference design PCB's. The Brain Power PCB is shorter than the reference design, thereby reducing height issues on custom/special applications. They also require fewer components, thus lowering cost and making it faster to build since it needs less time on the assembly line. Using the Brain Power PCB's not only improve overclocking it should reduce costs and increase productivity on the assembly line! Companies like Corsair have noticed the advantages of the PCB and last week stated for the record that the Corsair XMS XL line would be moving over to a new PCB. Corsair isn't going to issue a new version number for the "new" PCB XMS XL modules, so getting one would be blind luck and several weeks down the road. Don't forget they have to clear out their stock of the reference design and then move them off the store shelves. This could take weeks to months depending on market sales.

Who knows if OCZ and PMI used the Brain Power PCB's to cut costs and raise profit margins or if they saw the performance gains from internal testing. That does not matter now; all that does matter is that OCZ and PQI are currently producing the best overclocking PC-3200 low latency modules on the market hands down. All thanks to their choice of PCB's used to build their modules on!

Legit Bottom Line:

When enthusiasts pick out their high performance memory they need to look at timings, IC's, and now the PCB's being used.


OCZ Technology Memory


PQI Turbo Memory