nV News talks about this issue in a news post called Tail Wags the Dog
"However, over the last few months many professional sites who take much effort in producing many wonderful reviews now seem to be coming under attack from the Hardware manufacturers, or in some cases ‘Ah you won’t get our hardware to review if you do not do it exactly this way’. Why you ask, well more often than not the results do not meet the expectations of the hardware manufacturers and that is fact!
I personally know of three other web sites that have been hit with the same response. One in particular stood up and told a very famous graphic's company "to take a long walk off of a short plank" and trust me this is the polite version. All of us who take time and effort to produce reviews sit down carefully to accurately report back what we see using the items in question."
Pressure put on hardware reviews sites to produce good reviews
it's deju vu all over again
if you don't pimp our stuff, we won't send you any more - I can can't im
gine a hardware site willing to write only favorable reviews just so the webmasters would get shiny new GF4s, 9700s, XP2400s,P4-2.8s, etc. or endlessly pimping a certain manufacturer like Dell 
I've seen a couple of reviews lately where they did it consumer report style - went out and bought the parts in the retail market - which is really the only way you can be sure of not getting cherry picked items - but what site (beside AT) could afford that?
Im still waiting to see an unbiased review of the X-10 multipurpose cam
if you don't pimp our stuff, we won't send you any more - I can can't im
gine a hardware site willing to write only favorable reviews just so the webmasters would get shiny new GF4s, 9700s, XP2400s,P4-2.8s, etc. or endlessly pimping a certain manufacturer like Dell I've seen a couple of reviews lately where they did it consumer report style - went out and bought the parts in the retail market - which is really the only way you can be sure of not getting cherry picked items - but what site (beside AT) could afford that?
Im still waiting to see an unbiased review of the X-10 multipurpose cam
<a href="http://www.heatware.com/eval.php?id=123" target="_blank" >Heatware</a>
Ya its pretty pathetic of hardware makers to pull that shit if you ask me. If i had one tell me i'm gonna do it this way or i won't recieve their product no more i'd say the last one i did is the last one i'll do and don't bother sending it. If i can't tell it how i see it from a non biased viewpoint then i don't want to review it. If something simply is a POS i want the readers to know that. If its a kick ass product i want them to know that too. Why cheat the consumers out of their hard earned cash just to make some million dollar company richer.. I say FVCK THAT! If they produce good stuff then they deserve a good review if its shit the review will tell that story also...
3DGPU Editorial-Industry Big-Wigs Playing Hardball
"We all know crap like this goes on behind the scenes, but few of us want to bother blowing the whistle because we know there will be significant fallout that could really hurt our careers and our sites. I remember writing a review of a speaker set for a site I worked for that was very thorough, very detailed and very honest. The problem was, the result was not the one that the manufacturer of the speakers was looking for, and as a result, they refused to supply any more speakers for review unless the rating was changed. The head of the site was a very solid guy with serious integrity, and he did not bow to the pressure. He told them to hit the road, and I've always thought highly of him for it.".
"We all know crap like this goes on behind the scenes, but few of us want to bother blowing the whistle because we know there will be significant fallout that could really hurt our careers and our sites. I remember writing a review of a speaker set for a site I worked for that was very thorough, very detailed and very honest. The problem was, the result was not the one that the manufacturer of the speakers was looking for, and as a result, they refused to supply any more speakers for review unless the rating was changed. The head of the site was a very solid guy with serious integrity, and he did not bow to the pressure. He told them to hit the road, and I've always thought highly of him for it.".