I've had in mind to get myself some proper memory cards for some time now .. you can never have too many I reckon ... so this just happened the other day(or was it today .. work has mushed my brain these past two weeks).

Anyhow, I got myself a 32G Sandisk Extreme card to get the D800 working at least.
I have a handful of CF cards, some of which work badly, and others that don't on the D800 .. the real painful card is this noname brand Patriot card in the LX Series.
A brilliant card on the D300, even tho it's a no name brand, is super fast and allows full use of the D300's ability.
I've had this card now for about 3 years or so .. maybe more, it's been so long .. it has been my workhorse card since I got it for the D300.

BUT!! it just doesn't work on the D800. Have no idea as to why, but the camera just reads Card Err on the top LCD.
So this card is stuck in the D300 and allows my 12 yo son to play at full speed on his D300!(he love this 6fps bizo .. the hoon! )

So this Patriot LX series card I know is fast, but exactly how fast was always a guess, up until I finally got myself a USB3 card reader now.

Patriot LX card @ 8Gig:

via the PC sees 70Mb/s read speeds, and just a whisker over 50Mb/s sustained write speeds.
This makes sense because on the D300, it allows full use of the buffer, and when that's full, it then continues along at the expected 1fps rate indefinitely until full. That is, you will tire before the camera reaches the 100 burst limit.
Actually!... I should clarify that last bit. You and I will tire before the 100 frame limit is reached, but my hoon 12 yo son won't

So back on the topic and reason for this post ... and the reason for this post is that once again, my expectations for an expensive purchase (or more accurately disappointingly excessive financial expenditure!) have not been realized again!
I read good things about these Lexars, and I can't see it .. all!

With the Lexar what I do see is massively fast read speeds:

Lexar Professional 32Gig 800x UDMA7 CF card:

via the PC this card reads at an astonishing 110Mb/s and hovers at 115Mb/s all too often.
This is backed up by the fact that if I blink, 2 or 3Gig of image files have been transferred to the PC, where my usual routine is(or was) to start the transfer and then make a cuppa.
But the time it's cooled down to a drinkable level, and I'm now back at the sink and washing the cup, there may be a few more files that need to be transferred, after which I'm ready to review and process, or not.
Very painful to transfer 8 Gig of files via USB2 .. and if you have USB3 capability do yourself the favour and get a USB3 reader!

So again via the PC, I can get up to about 37Mb/s write speeds to this supposedly fast (800x!!) card, which is about 50% slower than the no name Partiot CF card from all that long ago.
So the USB3 interface is not the issue, the card is. Rob Galbraith reckons he sees about 55Mb/s from the 600x version of this card! with a burst of 29 frames before the D800 buffer fills all the way and slows the shooting rate.
So I reckon I've probably done something wrong somewhere(which I'll investigate).
Card was formatted in camera, and on the PC shows 32Kb cluster sizes and all that jazz .. but all I see is an expensive failure so far, in terms of money spent v's any gain in performance.

But I had to do this anyhow, it's just that now that I know what I know, I wouldn't recommend this Lexar 800x bogus performance memory card based on what I've seen so far.
(if this changes by way of new info coming to light, I'll edit my post to suit the updated info)

I've had two 8G CF cards of A-Data fame for almost as long as time itself. These cards were originally purchased for use on a PDA for my mapping program, and speed was not a major issue way back then.
They were only used due to their capability to contain data, on the D300 this meant a few days worth of shooting easily.
On the D800, not only is 8G very little in the way of actual frames captured, but the speed of the card became a nightmare.
A single image would take minutes to write .. and so testing reveals why.

A-Data 8G CF card:

via the PC it has only evr achieved a top write speed of about 7Mb/s or less(on a good day ) .. so it's easy to see why it took so long to actually commit a single D800 file to it's memory modules.
USB3 is wasted on these old slow cards. Read speeds have only ever been at about the 15-17Mb/s, and I initially thought this was due to the USB2 interface, but with the USB3 reader, I see 17-19Mb/s .. not even 20Mb/s. Remembering though, that this is not a criticism, just an observation. The cards were never meant for any camera .. I didn't even have a camera back on '04 when I got them.
They simply ended up as redundant hardware for a device that no longer exists, and were kept as backup backups .. just in case.

And I have a Sandisk Extreme SD card of 32Gig capacity.
This one is also weird.

Sandisk Extreme 32Gig SD card:
Formatted in the exFat file system as it's supposed to be, the write speed is a consistent 33Mb/s flicking up to 35 every so often, but my take is that 33Mb/s is a good average.
This again is via the PC too.
Read speeds are interesting, and this has now happened on three occasions that I've tried it.
It starts off at about 35-40Mb/s and hovers there for short while(maybe 30sec or so), and then suddenly jumps up to 95Mb/s for no reason, and then settles down to about 70-75Mb/s for the remainder of the large-ish file transfer.

I had a stash of about 4Gig that I transferred to and from the PC to each card via Windows Explorer, each time clearing out the prefetch cache .. so whilst not 100% accurate, is a reasonable indicator as to what I see in real life.

D800 can't manage more than 15 frames in a burst at the highest quality image settings before it chokes under the weight of it's own data, no matter the card used. If anyone has any info as to why this may be, more folks may benefit from this than just myself.
Even the old slow A-Data manages this, as the 15 frames is a product of the camera's buffer, not the card. But once those 15 frames are shot, then it's matter of waiting for them all to be written to the card itself.
The D900s will be an old camera before that task is complete, so this is not something I ever expected to have to deal with in real life .. and why the Lexar card was purchased in the first place.
I can get 19 frames from the buffer if the raw files are set to compressed, and then 1fps after that.

The real annoyance is the once mighty Patriot card. Faster write speeds than the fast Lexar, that is much newer and much more expensive, even via the supposedly complimentary card reader.
I'd have expected the Lexar usb3 card reader to work better/faster with a similar branded card than I expect with a foreign card that barely even works with most hardware!

I've seen these Patriot cards for sale now for about $20 or so for the 16gig versions, but even with all this pseudo praise, the card is useless on a D800 .. just doesn't work.
And what's even more annoying, I can't format the Patriot via the Lexar reader, only via the USB2 reader I have .. but it writes a lot faster and reads fast enough. This is just weird.

Summary:

I don't hesitate to try no name gear. Usually you get what you pay for, and sometimes this can be a pleasant surprise.
What I hate is the disappointment of a supposedly superior piece of kit purchased at a premium price that doesn't deliver as it's supposed too!

.. things I need to do .... read up as to how to best extract more performance from the Lexar before I find myself in a situation where it may be required.

.. and things I'd like to know .. why does this stuff not work for no good reason? What was(and still is) a perfectly great card on the D300, is useless on the D800. Why do Nikon find the need to change stuff like this for no apparent advantage?

anyhow .. just some info if this helps anyone else too.