Today, I'm having a look at SilverStone's newest modular power supply:  The Strider ST75F.

The ST75F is the next model up in the Strider line from the 600W ST60F unit.  Like the ST60F, the ST75F is manufactured for SilverStone by Enhance Electronics.

Upon opening the box of the Strider, we are first greeted by a manual.  SilverStone manuals are nice in that they give us pretty useful information, and they're typically more detailed and technical than most power supply company's manuals.  Inside we find cross loading graphs, ripple voltage test circuit diagrams... really fun stuff!

Once we remove the manual from the box, we can see the power supply.  SilverStone attaches all of the modular cables to the housing when they ship the Strider units, so there's no separate box or nylon bag to hold the cables in.

The Strider comes in a black steel housing with a 120MM fan.  The "SilverStone" logo is stamped into the top of the power supply.  On the back of the unit is a large grill, while the front of the unit has the modular interface and a large decal displaying all of the receptacles of the interface and what each connector is to be used for.

Above and below are a couple pictures of the modular interface and the cables that come out of it.

Below I've taken all of the cables out of the modular interface so we can see the female receptacles.

Here's an inventory of the cables that come with the Strider ST75F:

With the higher end video cards that have come out this year, and even more to come, SilverStone decided it was time to juice up it's popular modular Strider product with this new 750W model.  The ST75 is modular, features four PCI-e connectors and has a continuous output rating of 750W.

You'll notice that the 3.3V and 5V combined load capability is unchanged from the ST60F, but the +12V rail OCP is now set to 18A across the board, and the combined +12V rail rating is now 648W, or 54A.

Each modular PCI-e cable has two PCI-e connectors on it and each connector is labeled "12V3", "12V3", "12V4", "12V4" (see above.) But the connectors are modular and there are two different interfaces on the PSU housing that they can plug into, are interchangable... so how do you know which is 12V3 and 12V4?

I tried tracing the wires on the modular interface PCB, but after a while, my eyes would cross and I never could figure out what went where (see above and below image) So I decided, since the main ATX was on 12V3, I'd put a 10A load on it. If I can put a 20A load on one particular PCI-e connector, then that particular connector couldn't be the PCI-e that was on the same rail as the 24-pin.

So I did and I found that the PCI-e connector to the far right, as the PSU is sitting fan up (as shown below,) is 12V4. The other PCI-e is 12V3.

Now that I know what connector goes to what label, I know how I'm going to set up the load tester.

For those who don't know how I go about testing power supplies; I use a SunMoon SM8800 power supply ATE (automated test equipment.) Essentially, it's a machine made specifically for the testing of ATX12V power supplies.  It can put up to 10 different static loads on up to 10 different rails at a time.  I can also ramp loads up and down and do short tests, etc. 

For the sake of a review, I just pre-program a few different loads into the tester and run each one for about a half an hour.  For the ST75F, I've programmed seven different loads ranging from 145.4W to 761.9W.  The seventh, and final test, is a crossload test with the +12V rails maxed out, and a minimal load on the 3.3V and 5V rails.

For more information about my testing methodology, read this.

So I plugged the 8-pin EPS+12V of the power supply into the 8-pin of the ATE for the +12V1 and +12V2 tests. Since the load on the 8-pin is split across two +12V rails, I pretty muched doubled up the load I put on that connector.

The +12V3 load is split up between the main ATX connector and one of the PCI-e connectors.  The +12V4 load is split up between the two PCI-e connectors plugged into the +12V4 interface of the ST75F.

Intake and exhaust temperatures are measured with a temperature probe at the intake fan and exhaust vent of the power supply.

Going from test 1 to 5, we see excellent voltage regulation.  During test 6, we see things break down a bit, but this can be for multiple reasons.  One of which being that we're actually a tad over spec at 761.9W.  The other is that resistance building up in the wire leads and modular connections of the power supply are causing voltages to drop.

To give you an idea of how much the SilverStone ST75F didn't like being loaded up to 761.9W, I shot this video.  You'll note how the voltage readings of each rail seem to bounce around considerably.

In retrospect, check out this video of the ST75F during test 7.  Only the 3.3V and 5V rails have been reduced from the previous test.  The 12V rails are still juiced up putting out 648W of power, yet the bounce in the voltage has been reduced significantly.  In fact, it's almost non-existent.  This tells us the problem we had seen in the video for test 6 is not likely caused by the voltage output rectifiers, because otherwise the bounce would be present regardless of the total power output of the PSU and consistant with the actual load on each rail.

Efficiency is pretty decent, but nothing really special now that we're seeing more and more power supplies that are consistantly over 80% efficient.  Only when the PSU was around 50% loaded did it give me efficiency over 80%.

The fan was very quiet and could barely be heard over the fan of the load tester.

Now were going to run the "hot" load tests. To perform the "hot load tests" I put a side panel on the case the PSU is mounted in and run a hose and an 80MM intake fan into the TAC CPU duct. The heat generated by the load tester is pumped into the other end of the hose.

The voltages seem to be unaffected by the high temperatures.  The fan did kick into high speed during test 5 and then to an even higher speed again during test 6, which explains the drop in intake temperature during those tests, but the fan was never really "too loud."

Now we've come to the part of the review where we test ripple. Ripple is what you call the small fluctuations in voltage that happens every ms or so that may not affect performance, but may kill your components in time.

Ripple is measured at the load by an USB Instruments Stingray DS1M12 . I use the Stingray as a medium between the data being spit out by the SunMoon load tester's Waveform Monitor output and my laptop. Each change in voltage is collected and reported every .2ms. The time divide on the graphs is 2ms (every square being 2ms) The voltage scale on the graph is .05V, or 50mV.

Strider ST75F	+3.3V	+5V	+12V1&2	+12V3	+12V4
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7

Ripple on the +12V rails never really gets too bad.  ATX12V specification has a tolerence of 120mV For +12V rails and at the worst, during test 6, we're only seeing about 75mV.  What's interesting is that once the 3.3V and 5V loads are lowered to the point where a crossload is created, during test 7, the ripple on the +12V rails, even though the load on those rails reman the same, is only about 30 or 40mV.

The +5V rail doesn't look as good.  ATX12V specification's tolerance for +3.3V and +5V rails is 50mV.  We hit 50mV as soon as test 3.  And the ripple on the +5V is as much as 80mV by test 6.

Now let's take a look at some inside shots of the ST75F....

From overhead, the ST75F doesn't look too different than the ST60F.  Note the use of two main transformers instead of just one.  Note the large Teapo primary cap in the center of the PCB.

You could hurt someone with the large ferrite coil on the primary side of in this thing.

Now we move over to the secondary side of the ST75F. No doubt this is a very neatly laid out power supply inside.   Below, we can see we have a number of Teapo and Su'Scon caps on the secondary side.

So now that we got those "inner-beauty" shots out of the way, let's go ahead and score this thing...

Performance (weight of 40%):  The voltage regulation was very good, to a point.  There's a lot of power available here, and certainly enough to power a pair of 8800GTX cards in most people's builds.  After seeing the voltages bounce around under full load, I do hesitate calling this PSU a 750W.  Perhaps a 700W rating is more realistic.  Efficiency is good, although not fantastic, and the unit does have active PFC.  The fact that this PSU is very quiet helps this PSU score a 8.5.

What keeps the ST75F from scoring a 10 was the instability under full load and the lack of 80% and up efficiency

Aesthetics (weight is 10%):  Here the SilverStone ST75F scores an 8.5.  All of the cables are sleeved, and certainly the PSU being modular makes the inside of a computer have more aesthetic appeal.  The flat black finish lacks flash, but it still looks good.  It's too bad the "SilverStone" that's stamped into the steel faces up against the top of the case so it can't be seen when installed in most cases.

Value (weight of 30%):  The ST75F sells for around $140.  Sometimes less.  That's a very good price for a 750W power supply.   Even if you think in the back of your head that this power supply only a 700W power supply, even a Tagan 700W or Seasonic 700W cost more than $140!  For this reason, the ST75F gets a value score of 9.

Functionality (weight is 20%):  For functionality, I give the ST75F a 9.5.  Of course, the fact that the PSU is modular is a major plus in this category.  But more than that, the cables are sleeved nicely, long, easy to manipulate.  The only thing that keeps this PSU from scoring a 10 in this category is the over all size of the PSU, which is 180MM (just over 7".)

That gives the SilverStone ST75F an overall score of 9.  A 9 means the ST75F squeaks by with a "jonnyGURU Recommended".

SUMMARY:

The ST75F is certainly an excellent effort with some really good features.  The unit is far from the quality in construction of the SilverStone Zeus ST75ZF and may have fallen short on efficiency and it's ability to provide stable voltages when fully loaded, but this shortcoming could be measured in mere millimeters.  It's still very solid all of the way up to 700W, can handle a crossload and is modular with some very nicely sleeved cables.  Wrap this up with a $140 price tag and you've got a pretty good option for your new G80 SLI build.

The GOOD:

• Modular
• Nicely Sleeved Cables
• Very Quiet 120MM Fan
• Four PCI-e Connectors
• Lots of Power For The Money

The BAD:

• A Little Shaky at High Loads

The MEDIOCRE:

• Efficiency is "decent" but not Stellar
• Flat Black Finish Only Works for Some People

Please feel free to discuss this review in the forums.